Composite material having sliding property

ABSTRACT

A composite material having sliding property is produced by applying, to a substrate, a material comprising a fluorine-containing ethylenic polymer having functional group which is prepared by copolymerizing (a) 0.05 to 30% by mole of at least one of fluorine-containing ethylenic monomers having at least one functional group selected from the group consisting of hydroxyl, carboxyl, a carboxylic salt group, a carboxylic ester group and epoxy, and (b) 70 to 99.95% by mole of at least one of fluorine-containing ethylenic monomers having no functional group mentioned above. The composite material having sliding property which is produced by applying, to the substrate, the material comprising the fluorine-containing polymer having an excellent adhesive property to the substrate without necessitating complicated steps.

TECHNICAL FIELD

The present invention relates to a composite material having sliding property which is produced by applying, to a substrate, a fluorine-containing polymer excellent in sliding property, non-sticking property, heat resistance, transparency (property for exhibiting clear surface pattern), water- and oil-repellency and particularly adhesive property to the substrate and utilizes particularly sliding property thereof.

BACKGROUND ART

Hitherto with respect to a heating surface of, for example, an iron in the field of domestic appliances, not only excellent heat resistance but also excellent sliding properties such as friction resistance and abrasion resistance have been demanded since it is used while being pressed onto clothes and slid thereon. Namely a material being excellent in sliding properties is required to be applied to such a portion.

As a material having sliding properties, generally there are engineering plastics such as polyacetal and PPS, silicon material and fluorine-containing material, particularly a fluorine-containing resin which are common materials and have been used practically.

However, there is a substantial problem that the fluorine-containing resin is insufficient in adhesion to a substrate of metal or glass due to its excellent non-sticking property.

Therefore in case where the fluorine-containing polymer is used in the form of a coating, there is a method of adhering a fluorine-containing resin to a substrate by roughening the surface of metal chemically or physically with expecting anchor effect between them. However this method requires much labor in the surface roughening itself, and though initial adhesion is possible, lowering of the anchor effect arises when a temperature change is made repeatedly and in case of use at high temperature.

Also a method for chemically activating a surface of a fluorine-containing resin by treating the surface with a solution prepared by dissolving metallic sodium in liquid ammonia has been proposed. However in that method, not only there is a fear that the solution itself causes environmental pollution but also there is a problem that its handling is attended with danger.

Further though a method for carrying out physical and chemical treatment such as plasma sputtering on a surface of a fluorine-containing resin has been proposed for activation of the resin surface, there is a problem that much labor is required for the treatment and an increase in cost is resulted.

Also in order to improve adhesion of a fluorine-containing resin coating, investigations with respect to addition of various components and formation of a primer layer have been made.

For example, there is a technique of adding an inorganic acid such as chromic acid to a coating composition containing a fluorine-containing polymer to form chemical conversion coating film on a surface of metal for enhancing adhesion of the composition (JP-B-63-2675). However since chromic acid contains hexahydric chromium, it cannot be said that such a technique is sufficient in view of safety in food and coating work. Further in case of use of other inorganic acids such as phosphoric acid, there was a problem that safety of a fluorine-containing resin coating composition is damaged.

Use of a coating composition containing a fluorine-containing resin as a primer, in which heat resistant resins such as polyamide imide, polyimide, polyethersulfone and polyether ether ketone and in addition, a metal powder are added instead of the above-mentioned inorganic acid, has been studied (JP-A-6-264000). Inherently there is almost no compatibility between a fluorine-containing polymer and a heat resistant resin. Therefore there arises a phase separation in a coating film, thus easily causing intercoat adhesion failure between the primer and the top coat of the fluorine-containing resin. Further film defects such as pin holes and cracks arise easily at the time of processing at high temperature or during use due to a difference in heat shrinkage between the fluorine-containing resin and the heat resistant resin or due to lowering of elongation of the coating film by the addition of the heat resistant resin. Also since those heat resistant resins are colored brown by baking, property for exhibiting clear surface pattern is poor and it is difficult to use them for applications requiring white and vivid colors and transparency. Further when the heat resistant resin is blended, non-sticking property and friction resistance which the fluorine-containing polymer inherently possesses are lowered.

Also for adhesion of a fluorine-containing resin coating composition to a glass, etc. requiring transparency, an improvement of the adhesion has been tried by treating the substrate with a silane coupling agent or adding a silicone resin to the fluorine-containing resin coating composition (JP-B-54-42366, JP-A-5-177768). However enhancement of adhesion is insufficient, heat resistance is lowered and separation of a coating film, foaming and coloring arise easily at sintering or in use at high temperature.

On the contrary, fluorine-containing resin coating compositions prepared by copolymerizing a hydrocarbon monomer (containing no fluorine) containing functional group such as hydroxyl or carboxyl have been discussed. However since those coating compositions were originally studied mainly for a purpose of weather resistance, sliding properties (particularly friction resistance) directed by the present invention are insufficient and it is difficult to use them for application requiring heat resistance (for example, 200° to 350° C.).

Namely with respect to a polymer prepared by copolymerizing a hydrocarbon monomer (containing no fluorine) having functional group, thermal decomposition easily occurs on components of the monomer at the time of processing at high temperature or during use, and thus coating film failure, coloring, foaming, separation, etc. arise, which makes it impossible to attain purposes of coating a fluorine-containing resin.

Further fluorine-containing polymers are generally insufficient in mechanical strength and dimensional stability, and high in price. In order to minimize those disadvantages and make the best use of the above-mentioned merits which the fluorine-containing polymer possesses inherently, investigations have been made also with respect to its use in the form of film.

However the fluorine-containing polymer inherently has low adhesive force, and it is difficult to adhere the fluorine-containing polymer in the form of film directly to other material (substrate). For example, even if the adhering is tried by thermo-processing, adhesive strength of the fluorine-containing polymer is not enough, or even if the polymer has adhesive force to a certain extent, such an adhesive force is apt to vary depending on kind of the substrate. Thus in many cases, reliability on the adhesive strength of the fluorine-containing polymer has been not so enough.

In order to adhere the fluorine-containing polymer film to a substrate, mainly the following methods have been studied:

1. a method for physically roughening a surface of substrate by sand blasting, etc.,

2. a method for surface-treating a fluorine-containing resin film by chemical treatment such as sodium etching, plasma treatment, photochemical treatment, etc.,

3. a method for adhering by using an adhesive, and other methods. With respect to the methods 1 and 2 above, other steps are required, and the steps are complicated and productivity is poor. Also kinds and shapes of substrates are restricted. Further the obtained adhesive force is insufficient, and also there easily occur a problem with appearance (property for exhibiting clear surface pattern) of the obtained composite materials such as coloring and color. Also the method of using a chemical such as sodium etching has a problem with safety.

Use of an adhesive in the method 3 above has also been discussed. A usual hydrocarbon type (containing no fluorine) adhesive does not have enough adhesive property and its heat resistance is insufficient. Thus a hydrocarbon type adhesive cannot stand under conditions for adhering of a fluorine-containing polymer film which requires molding and processing at high temperature, and peeling due to decomposition of the adhesive and coloring occur. Since the above-mentioned laminated article produced by using an adhesive also is insufficient in heat resistance, chemical resistance and water resistance, it cannot maintain adhesive force due to a change in temperature and environment, and lacks in reliability.

On the contrary, adhesion by using an adhesive composition comprising a fluorine-containing polymer having functional group is discussed.

For example, it is reported that a fluorine-containing polymer prepared by graft-polymerizing, to the fluorine-containing polymer, a hydrocarbon monomer which has carboxyl represented by maleic anhydride and vinyltrimethoxysilane, a residual group of carbonic acid, epoxy or a hydrolyzable silyl group, is used as an adhesive (for example, JP-A-7-18035, JP-A-7-25952, JP-A-7-25954, JP-A-7-173230, JP-A-7-173446, JP-A-7-173447) and that an adhesive composition comprising a fluorine-containing copolymer prepared by copolymerizing a hydrocarbon monomer having functional group such as hydroxyalkyl vinyl ether with tetrafluoroethylene or chlorotrifluoroethylene and an isocyanate hardening agent is cured and used as an adhesive between vinyl chloride resin and corona-discharged ETFE (for example, JP-A-7-228848).

The above-mentioned adhesive composition comprising a fluorine-containing resin prepared by graft-polymerizing or copolymerizing a hydrocarbon monomer having functional group does not have enough heat resistance, and thus at the time of processing a composite material comprising the adhesive composition and a fluorine-containing resin film at high temperature or during use at high temperature, decomposition and foaming occur, thereby causing reduction of adhesive strength, peeling and coloring. In case of the adhesive composition disclosed in JP-A-7-228848, it is necessary to corona-discharge the fluorine-containing resin film.

As mentioned above, no composite materials having sliding properties which assure strong adhesion to a substrate have been obtained.

In view of the above-mentioned facts, an object of the present invention is to provide composite materials having sliding properties (friction resistance) which are produced by applying, to a substrate, a material comprising a fluorine-containing polymer being excellent in adhesion to the substrate without necessitating complicated steps.

Further an object of the present invention is to obtain the composite materials having sliding properties excellent in stain-proofing property, non-sticking property, transparency (property for exhibiting clear surface pattern), anti-bacterial property, water- and oil-repellency, stain removable property, chemical resistance, rust-preventing property and resistance to energy rays.

DISCLOSURE OF THE INVENTION

The present invention relates to a composite material having sliding properties which is produced by applying, to a substrate, a material comprising a fluorine-containing ethylenic polymer having functional group and prepared by copolymerizing:

(a) 0.05 to 30% by mole of at least one of fluorine-containing ethylenic monomers having at least one functional group selected from the group consisting of hydroxyl, carboxyl, a carboxylic salt group, a carboxylic ester group and epoxy and

(b) 70 to 99.95% by mole of at least one of fluorine-containing ethylenic monomers having no functional group mentioned above.

In that case, it is preferable that the above-mentioned fluorine-containing ethylenic monomer (a) having functional group is at least one of fluorine-containing ethylenic monomers represented by the formula (1):

CX₂═CX¹—R_(f)—Y  (1)

wherein Y is —CH₂OH, —COOH, a carboxylic salt group, a carboxylic ester group or epoxy, X and X¹ are the same or different and each is hydrogen atom or fluorine atom, R_(f) is a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing oxyalkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having ether bond and 1 to 40 carbon atoms or a fluorine-containing oxyalkylene group having ether bond and 1 to 40 carbon atoms.

Further it is preferable that the fluorine-containing ethylenic monomer (b) having no functional group mentioned above is tetrafluoroethylene.

Further it is preferable that the fluorine-containing ethylenic monomer (b) having no functional group mentioned above is a monomer mixture of 85 to 99.7% by mole of tetrafluoroethylene and 0.3 to 15% by mole of a monomer represented by the formula (2):

 CF₂═CF—R_(f) ¹  (2)

wherein R_(f) ¹ is CF₃ or OR_(f) ², in which R_(f) ² is a perfluoroalkyl group having 1 to 5 carbon atoms.

In the present invention, it is preferable that the fluorine-containing ethylenic polymer having functional group is applied to a substrate in the form of a coating composition, an aqueous dispersion, a powder coating or a film.

The substrate may be a metallic substrate, a ceramic substrate of glass or porcelain or a synthetic resin substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic plan view of an adhered sample made to measure adhesive strength in Example 7 of the present invention.

FIG. 2 is a diagrammatic perspective view of a test sample used to measure adhesive strength in Example 7 of the present invention.

FIG. 3 is a diagrammatic perspective view of a laminated article made to produce a test piece subjected to adhesion test (T-type peeling test) in the present invention.

FIG. 4 is a diagrammatic perspective view of a test piece subjected to adhesion test (T-type peeling test) in the present invention.

FIG. 5 is a diagrammatic perspective view of a test piece subjected to adhesion test (tensile shearing test) in the present invention.

FIG. 6 is a diagrammatic view of a test device used for adhesion test (tensile shearing test) in the present invention.

FIG. 7 is a diagrammatic cross-sectional view of a laminated test plate made in Example 15 of the present invention.

FIG. 8 is a diagrammatic cross-sectional view of a three-layered laminated article made in Example 15 of the present invention.

FIG. 9 is a diagrammatic cross-sectional view of a laminated article made in Comparative Example 10 of the present invention.

FIG. 10 is a diagrammatic cross-sectional view of a laminated test plate for making a laminated article in Example 16 of the present invention.

FIG. 11 is a diagrammatic cross-sectional view of a laminated article made in Example 16 of the present invention.

FIG. 12 is a diagrammatic cross-sectional view of a laminated article subjected to T-type peeling test in Example 16 of the present invention.

FIG. 13 is a diagrammatic cross-sectional view of a laminated article subjected to T-type peeling test in Comparative Example 11 of the present invention.

FIG. 14 is a diagrammatic cross-sectional view of a laminated test plate made in Comparative Example 12 of the present invention.

FIG. 15 is a diagrammatic perspective view of a test piece subjected to non-stickiness test in the present invention.

FIG. 16 is a diagrammatic cross-sectional view of a laminated test plate for making a laminated article in Example 21 of the present invention.

FIG. 17 is a diagrammatic cross-sectional view of a laminated article made in Example 21 of the present invention.

FIG. 18 is a diagrammatic cross-sectional view of a laminated article subjected to T-type peeling test in Example 21 of the present invention.

FIG. 19 is a diagrammatic perspective view of an aluminum plate having a coating film obtained in Example 25 of the present invention for measuring adhesive strength.

FIG. 20 is a diagrammatic perspective view of a test sample made for measuring adhesive strength in Example 25 of the present invention.

FIG. 21 is a diagrammatic cross-sectional view of a laminated test plate made in Example 28 of the present invention.

FIG. 22 is a diagrammatic cross-sectional view of a three-layered laminated article made in Example 28 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The composite material having sliding properties of the present invention is one produced by applying, to a substrate, a material comprising a fluorine-containing ethylenic polymer having functional group and prepared by copolymerizing:

(a) 0.05 to 30% by mole of at least one of fluorine-containing ethylenic monomers having at least one functional group selected from the group consisting of hydroxyl, carboxyl, a carboxylic salt group, a carboxylic ester group and epoxy and

(b) 70 to 99.95% by mole of at least one of fluorine-containing ethylenic monomers having no functional group mentioned above.

The above-mentioned material comprising the fluorine-containing ethylenic polymer having functional group has surprisingly strong adhesion in the form of a coating or film to substrates of metal, glass, etc. even without use of an adhesive, surface-treatment on the substrate, formation of a primer layer and addition of a component having adhesive property in the material.

With respect to the fluorine-containing ethylenic polymer having functional group which is used for preparing the composite material of the present invention, it is important to copolymerize (a) the above-mentioned fluorine-containing ethylenic monomer having functional group and (b) the fluorine-containing ethylenic monomer having no functional group mentioned above to introduce the functional group into the fluorine-containing polymer, thereby making it possible to give excellent adhesive force directly to surfaces of various substrates, to which adhesion has been difficult or impossible. Namely as compared with a fluorine-containing polymer prepared by copolymerizing a non-fluorine-containing monomer having functional group, the fluorine-containing polymer of the present invention is excellent in heat resistance, and decomposition at processing at high temperature (for example, 200° to 400° C.) can be inhibited more and a large adhesive strength can be obtained. Further a coating layer being free from coloring, foaming, pin hole caused thereby and leveling failure can be formed on a substrate. Also in case where the composite material is used at high temperature, adhesive property is maintained and a coating layer failure such as coloring, whitening, foaming or pin hole is difficult to arise.

The above-mentioned fluorine-containing polymer having functional group has excellent characteristics such as not only heat resistance thereof but also sliding properties (friction resistance), stain-proofing property, chemical resistance, non-sticking property and weather resistance of a fluorine-containing polymer and can give such excellent characteristics to a coating film without lowering them.

Then the fluorine-containing ethylenic polymer having functional group which is a material for the composite material of the present invention is explained below.

The functional group of the fluorine-containing ethylenic polymer having functional group is at least one functional group selected from the group consisting of hydroxyl, carboxyl, a carboxylic salt group, a carboxylic ester group and epoxy, and provides the polymer with adhesion to various substrates by its effect. Kinds and combination of the functional groups are optionally selected depending on kind of a surface of the substrate and purpose and application. From the viewpoint of heat resistance, hydroxyl is most preferable.

Examples of the preferred fluorine-containing ethylenic monomer (a) having functional group which is one of components constituting the fluorine-containing ethylenic polymer having functional group are fluorine-containing ethylenic monomers having functional group which are represented by the formula (1):

CX₂═CX¹—R_(f)—Y  (1)

wherein Y is —CH₂OH, —COOH, a carboxylic salt group, a carboxylic ester group or epoxy, X and X¹ are the same or different and each is hydrogen atom or fluorine atom, R_(f) is a divalent alkylene group having 1 to 40 carbon atoms, a fluorine-containing oxyalkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having ether bond and 1 to 40 carbon atoms or a fluorine-containing oxyalkylene group having ether bond and 1 to 40 carbon atoms.

Examples of the fluorine-containing ethylenic monomer (a) having functional group are one represented by the formula (3):

CF₂═CF—R_(f) ³—Y  (3)

wherein Y is as defined in the above formula (1), R_(f) ³ is a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms or OR_(f) ⁴, in which R_(f) ⁴ is a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms or a divalent fluorine-containing alkylene group having ether bond and 1 to 40 carbon atoms, one represented by the formula (4):

CF₂═CFCF₂—OR_(f) ⁵—Y  (4)

wherein Y is as defined in the above formula (1), R_(f) ⁵ is a divalent fluorine-containing alkylene group having 1 to 39 carbon atoms or a divalent fluorine-containing alkylene group having ether bond and 1 to 39 carbon atoms, one represented by the formula (5):

CH₂═CFCF₂—R_(f) ⁶—Y  (5)

wherein Y is as defined in the above formula (1), R_(f) ⁶ is a divalent fluorine-containing alkylene group having 1 to 39 carbon atoms or OR_(f) ⁷, in which R_(f) ⁷ is divalent fluorine-containing alkylene group having 1 to 39 carbon atoms or a divalent fluorine-containing alkylene group having ether bond and 1 to 39 carbon atoms, one represented by the formula (6):

CH₂═CH—R_(f) ⁸—Y  (6)

wherein Y is as defined in the above formula (1), R_(f) ⁸ is a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms, and the like monomer.

From the viewpoint that copolymerizability with the fluorine-containing ethylenic monomer (b) having no functional group mentioned above is comparatively good and that heat resistance of the obtained polymer is not lowered remarkably, the fluorine-containing ethylenic monomers having functional group and represented by the formulae (3) to (6) are preferable.

Among them, from the viewpoint of copolymerizability with the fluorine-containing ethylenic monomer (b) having no functional group mentioned above and heat resistance of the obtained polymer, the compounds of the formulae (3) and (5) are preferable, and the compound of the formula (5) is particularly preferable.

Examples of the fluorine-containing ethylenic monomer having functional group and represented by the formula (3) are:

and the like.

Examples of the fluorine-containing ethylenic monomer having functional group and represented by the formula (4) are:

and the like.

Examples of the fluorine-containing ethylenic monomer having functional group and represented by the formula (5) are:

and the like.

Examples of the fluorine-containing ethylenic monomer

having functional group and represented by the formula (6) are:

CH₂═CHCF₂CF₂CH₂CH₂COOH,

CH₂═CHCF₂₄CH₂CH₂CH₂OH,

CH₂═CHCF₂₆CH₂CH₂COOCH₃,

and the like.

In addition, there are

and the like.

The fluorine-containing ethylenic monomer (a) having functional group is copolymerized with the fluorine-containing ethylenic monomer (b) having no functional group which the monomer (a) possesses. The fluorine-containing ethylenic monomer (b) is preferably selected from monomers having no functional group. The monomer (b) can be optionally selected from known monomers, and gives the polymer chemical resistance, non-sticking property and stain-proofing property in addition to excellent friction resistance and heat resistance.

Examples of the fluorine-containing ethylenic monomer (b) are tetrafluoroethylene, a monomer represented by the formula (2): CF₂═CF—R_(f) ¹, wherein R_(f) ¹ is CF₃ or OR_(f) ², in which R_(f) ² is a perfluoroalkyl group having 1 to 5 carbon atoms, chlorotrifluoroethylene, vinylidene fluoride, vinyl fluoride, hexafluoroisobutene,

 CH₂═CFCF₂_(n)X², CH₂═CHCF₂_(n)X²,

wherein X² are selected from hydrogen atom, chlorine atom and fluorine atom, n is an integer of 1 to 5, and the like.

In addition to the fluorine-containing ethylenic monomer (a) having functional group and the fluorine-containing ethylenic monomer (b) having no functional group mentioned above, an ethylenic monomer having no fluorine atom may be copolymerized in the range of not lowering sliding properties, heat resistance and non-sticking property. In that case, it is preferable that the ethylenic monomer having no fluorine atom is selected from ethylenic monomers having not more than 5 carbon atoms in order not to lower heat resistance. Examples of such an ethylenic monomer are ethylene, propylene, 1-butene, 2-butene, and the like.

A content of the fluorine-containing ethylenic monomer (a) having functional group in the fluorine-containing ethylenic polymer having functional group which is used in the present invention is from 0.05 to 30% by mole on the basis of the total amount of monomers in the polymer. The content of the monomer (a) is optionally selected depending on kind of the surface of a substrate requiring sliding properties, shape of the substrate, coating method, film forming method and conditions and further depending on purposes and applications of equipment and member to which the polymer is applied. The content of the fluorine-containing ethylenic monomer (a) having functional group is preferably from 0.05 to 20% by mole, particularly preferably from 0.1 to 10% by mole.

When the content of the fluorine-containing ethylenic monomer (a) having functional group is less than 0.05%, sufficient adhesion to the substrate surface is difficult to obtain, and separation easily occurs due to temperature change and permeation of chemicals. When more than 30% by mole, heat resistance is lowered and there occur adhesion failure, coloring, foaming and pin hole at sintering at high temperature or during use at high temperature, thus easily lowering property for exhibiting clear surface pattern and causing separation of a coating layer and elution due to decomposition.

Examples of the preferred fluorine-containing ethylenic polymer having functional group used in the present invention are as follows.

(I) A polymer comprising 0.05 to 30% by mole of the fluorine-containing ethylenic monomer (a) having functional group and 70 to 99.95% by mole of tetrafluoroethylene (reactive PTFE).

The polymer is the most excellent in sliding properties (friction resistance, abrasion resistance), non-sticking property, heat resistance and chemical resistance and further is superior from the viewpoint of stain-proofing property.

(II) A polymer comprising 0.05 to 30% by mole of the fluorine-containing ethylenic monomer (a) having functional group based on the total amount of monomers, and further based on the total amount of monomers excluding the monomer (a), 85 to 99.7% by mole of tetrafluoroethylene and 0.3 to 15% by mole of the monomer represented by the formula (2):

CF₂═CF—R_(f) ¹  (2)

wherein R_(f) ¹ is CF₃ or OR_(f) ², in which R_(f) ² is a perfluoroalkyl group having 1 to 5 carbon atoms. For example, there is a tetrafluoroethylene-perfluoro(alkyl vinyl ether) polymer having functional group (reactive PFA) or a tetrafluoroethylene-hexafluoropropylene polymer having functional group (reactive FEP).

The polymer has sliding properties, non-sticking property, heat resistance and chemical resistance nearly equivalent to those of the above-mentioned reactive PTFE (I), and further is superior from the points of possessing transparency and being melt-processable and from the viewpoint that even when coated in the form of coating, it is possible to make the coating film transparent and its surface smooth by heat.

(III) A polymer comprising 0.05 to 30% by mole of the fluorine-containing ethylenic monomer (a) having functional group based on the total amount of monomers, and further based on the total amount of monomers excluding the monomer (a), 40 to 80% by mole of tetrafluoroethylene, 20 to 60% by mole of ethylene and 0 to 15% by mole of other copolymerizable monomer (ethylene-tetrafluoroethylene polymer having functional group (reactive ETFE)).

The polymer is superior from the viewpoint of excellent sliding properties, heat resistance, non-sticking property, weather resistance and transparency, and further excellent mechanical strength, hardness and rigidity and from the point that molding and combining with other substrate (lamination, etc.) are easy because of good melt-flowability.

The above-mentioned fluorine-containing ethylenic polymers having functional group can be prepared by copolymerizing the fluorine-containing ethylenic monomer (a) having functional group and the fluorine-containing ethylenic monomer (b) having no functional group through known polymerization methods. Among them, radical copolymerization method is mainly used. Namely means for initiating the polymerization is not particularly limited if the polymerization advances radically. For example, the polymerization is initiated by an organic or inorganic radical polymerization initiator, heat, light, ionizing radiation, etc. The polymerization can be carried out by solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, or the like. A molecular weight of the polymer is regulated by a concentration of the monomers used in the polymerization, a concentration of the initiator, a concentration of a chain transfer agent and polymerization temperature. Amounts of components of the prepared polymer can be regulated by amounts of monomers used.

The fluorine-containing ethylenic polymer having functional group and explained above can be made into various forms as a material to be applied to a substrate. Represented examples of its application are a coating material and a material in the form of film. The polymer may be formed into a molded article.

In the composite material having sliding properties of the present invention, it is preferable that a layer containing a filler is provided on the outermost surface in order to enhance abrasion resistance.

Particularly in case where the outermost surface comprises the fluorine-containing ethylenic polymer having functional group, irrespective of being in the form of a coating or film, it is preferable to contain a filler in the outermost layer to improve mechanical strength, to increase surface hardness, to lower heat shrinkage, and then to increase abrasion resistance.

In that case, particularly in case where the outermost layer comprises a reactive PTFE, reactive PFA, reactive FEP or reactive ETFE, it is preferable to contain a filler in the outermost layer to improve mechanical strength, to increase surface hardness, to increase hardness at heating, to lower heat shrinkage, and then to increase abrasion resistance.

Further in case where a primer layer or film comprising only the above-mentioned fluorine-containing ethylenic polymer having functional group is applied to a substrate and thereon a coating or film comprising only a fluorine-containing ethylenic polymer having no functional group is applied as an outermost layer, it is preferable to contain a filler in the outermost layer to improve mechanical strength, to increase surface hardness, to lower heat shrinkage, and then to increase abrasion resistance.

In that case, particularly when the outermost layer comprises PTFE, PFA, FEP or ETFE, it is preferable to contain a filler in the outermost layer to improve mechanical strength, to increase surface hardness, to increase hardness at heating, to lower heat shrinkage, and then to increase abrasion resistance.

Examples of the filler to be mixed for the purpose of improving abrasion resistance are:

metals and metal fibers represented by stainless steel, iron, nickel, lead, copper, gold, silver, aluminum, molybdenum, rare earth cobalt and boron fiber;

carbons represented by carbon black, graphite, carbon fiber, activated carbon, hollow carbon beads and coke;

oxides represented by silica, alumina, titanium oxide, iron oxide, zinc oxide, magnesium oxide, tin oxide, antimony oxide, and the like;

hydroxides such as aluminum hydroxide and magnesium hydroxide;

carbonates such as calcium carbonate, magnesium carbonate and zinc carbonate;

sulfates such as calcium sulfate, gypsum fiber, barium sulfate, magnesium sulfate and MOS (basic magnesium sulfate in the form of fiber);

silicates represented by glass, hollow glass beads, glass fiber, talc, mica, kaoline, calcium silicate, wollastonite, xonotlite, PMF (a kind of slag fiber which is a mixture of alumino-silicate calcium and MgO), and the like;

borates such as aluminum borate, magnesium borate and calcium borate;

titanates such as potassium titanate and barium titanate;

nitrides such as aluminum nitride and silicon nitride;

carbides such as silicon carbide and titanium carbide;

sulfides such as molybdenum disulfide, molybdenum trisulfide, tungsten disulfide, zinc sulfide and cadmium sulfide;

phosphates such as calcium phosphate and iron phosphate;

ferrites such as barium ferrite, calcium ferrite and strontium ferrite;

and the like.

Those inorganic fillers are in the form of fiber, whisker, needle, powder, granule, bead, and the like.

Examples of an organic filler are organic fibers such as aramide fiber, polyalylate fiber and phenolic fiber; thermosetting resins such as polyimide, phenolic resin and COPNA resin; and the like.

Among them, preferred are carbon fibers remarkably enhancing mechanical properties (particularly strength and modulus of elasticity), dimensional stability and abrasion resistance and giving electric conductivity, glass fillers maintaining insulating property and enabling mechanical properties, dimensional stability and abrasion resistance to be remarkably enhanced, whiskers maintaining flexibility and sealing property of a fluorine-containing resin, giving a molded article having surface smoothness and enabling mechanical strength, dimensional stability and abrasion resistance to be remarkably improved, inorganic fillers having cleavage property and lubricity, thus giving lubricity to a composition and molded article and lowering a friction coefficient, and organic fibers which have a low hardness and a property of being hard to injure a counterpart material (soft metal, etc.) on a sliding surface particularly when the composition is used as a sliding part and can give mechanical properties, dimensional stability and abrasion resistance to a molded article.

In the present invention, the above-mentioned fluorine-containing ethylenic polymer having functional group can be applied to a substrate in the form of a coating to give a composite material having sliding property.

In the present invention, in case of use in the form of a coating, the polymer is capable of being in the form of aqueous dispersion, organic solvent dispersion, powder (including granulate), organosol or an aqueous emulsion of organosol. Among them, from environmental and safety points of view, it is preferable to apply in the form of an aqueous dispersion or powder (powder coating).

The coating may be applied so that excellent adhesive property of the fluorine-containing ethylenic polymer having functional group to the substrate is exhibited. The coating may be applied in one layer or as a primer.

In the present invention, the aqueous dispersion for fluorine-containing coating composition is prepared by dispersing, in water, particles of the above-mentioned fluorine-containing ethylenic polymer having functional group. By introducing a functional group in the fluorine-containing polymer, dispersion stability of fine particles in the aqueous dispersion is enhanced and a coating composition having good storage stability can be obtained, and further leveling property and transparency of a coating film are enhanced.

As the fluorine-containing ethylenic polymer having functional group, from the viewpoint of non-sticking property, heat resistance and stain-proofing property in addition to sliding property, the reactive PTFE (I) is preferred and from the viewpoint of heat resistance, transparency and non-sticking property, the reactive PFA or reactive FEP (II) is preferred.

The above-mentioned aqueous dispersion is preferably a composition in a state of 0.01 to 1.0 μm fine particles of the polymer being dispersed in water. Usually a surfactant may be blended in the aqueous dispersion for the purpose of dispersion stability. Also to the aqueous dispersion can be added additives to be used usually such as pigment, surfactant, anti-foaming agent, viscosity control agent and leveling agent in amounts not lowering remarkably sliding property, non-sticking property, heat resistance, chemical resistance and stain-proofing property.

The aqueous dispersion for fluorine-containing coating composition can be prepared through various methods. Examples of the method are, for instance,

a method wherein a powder of the fluorine-containing polymer having functional group and prepared by suspension polymerization is finely pulverized and then the pulverized powder is dispersed homogeneously into an aqueous dispersion medium with a surfactant,

a method wherein a fluorine-containing aqueous dispersion is prepared at the same time as emulsion polymerization and further a surfactant and additives are added as case demands, and the like methods. From the viewpoint of productivity and quality (for making particle size smaller and more uniform), a method of preparing an aqueous dispersion directly by emulsion polymerization is preferred.

A concentration of the polymer in the aqueous dispersion varies depending on intended coating thickness, concentration and viscosity of a coating composition, coating method, etc., and may be usually selected in the range of from about 5% by weight to about 70% by weight.

The coating method is not particularly limited. The coating may be carried out by brush coating, spray coating, roll coating or the like, followed by drying and then sintering at a temperature of not less than the melting point of the polymer and not more than its decomposition temperature depending on kind of the polymer.

The coating thickness may be selected depending on application, purpose, substrate, etc. For example, the coating thickness is from about 5 μm to about 200 μm, preferably from 10 to 100 μm.

The powder coating composition of the present invention comprises a powder of the above-mentioned fluorine-containing ethylenic polymer having functional group.

Further from the viewpoint of heat resistance, corrosion resistance, chemical resistance and non-sticking property in addition to sliding property, the reactive PFA or reactive FEP (II) is preferred, and from the viewpoint of non-sticking property, processability and transparency, the reactive ETFE (III) is preferred.

As the fluorine-containing powder coating composition, there can be used preferably one in the form of powder or in the granular form having a particle size of 10 to 1,000 μm and an apparent density of 0.3 to 1.2 g/cc.

To the fluorine-containing powder coating composition can be added optionally additives in an amount not lowering remarkably characteristics such as sliding property, non-sticking property and heat resistance of the fluorine-containing resin. Examples of the additives are, for instance, pigments such as carbon powder, titanium oxide and cobalt oxide; reinforcing agents such as glass fiber powder, carbon fiber powder and mica; amine anti-oxidant; organic sulfur compound; organotin anti-oxidant; phenolic anti-oxidant; thermal stabilizer such as metal soap; leveling agent; anti-static agent; and the like.

The fluorine-containing powder coating composition and the additives may be admixed in the form of powder (dry method) or in the form of slurry (wet method), and the mixing in the form of powder is preferred. As the mixing equipment, there can be used a conventional mixer or pulverizer, for example, a sand mill, V blender, ribbon blender or the like.

The fluorine-containing powder coating composition is generally coated by electrostatic spray coating, fluid-bed dip coating, rotolining, etc., and then sintered at a temperature of not less than the melting point of the polymer and not more than its decomposition temperature depending on kind of the polymer, and thus a good coating film can be formed.

In general in case of electrostatic powder spray coating, a coating film having a thickness of 10 to 200 μm is formed, and in case of rotolining, a coating film having a thickness of 200 to 1,000 μm is formed.

Further the fluorine-containing ethylenic polymer having functional group which is used for a fluorine-containing coating material can be also used, by utilizing its adhesive property, as a primer layer for a fluorine-containing coating composition which has good heat resistance at the time when applying a fluorine-containing resin having no functional group and being excellent in sliding property on surfaces of substrates such as metal and glass. An obtained composite material having sliding property comprises a primer layer of a fluorine-containing ethylenic polymer having functional group on a substrate and a top coat layer of a fluorine-containing resin having no functional group. It is a matter of course that a fluorine-containing ethylenic polymer having functional group may be used as a top coat layer.

The primer for a fluorine-containing coating composition comprises the above-mentioned fluorine-containing ethylenic polymer having functional group.

As the primer, the same fluorine-containing polymer as mentioned above can be used. The primer is selected optionally depending on kind of a substrate surface, kind of the fluorine-containing polymer to be applied through the primer (kind of a top coat), etc. It is preferable in general that the primer for a fluorine-containing coating composition is one which has the same structure as the fluorine-containing polymer to be applied thereon and contains a functional group.

That combination of the primer and top coat assures good compatibility between the fluorine-containing polymer to be used as the primer and the fluorine-containing polymer to be applied thereon, and can give not only good adhesion to the substrate surface but also good intercoat adhesive strength between the primer layer and the top coat layer. Also even in case of the use at high temperature, unlike the case where the primer mixed with other resin component is used, intercoat adhesion failure to be caused due to a difference in thermal shrinkage between the polymers, cracking, pin hole, etc. are hard to arise. Further since the whole coating film comprises the fluorine-containing polymer, it can be used sufficiently for applications requiring transparency and vivid coloring. Still further excellent sliding property, non-sticking property, heat resistance, chemical resistance and friction resistance can be exhibited more effectively even if a layer of fluorine-containing polymer having no functional group is formed on the outermost surface of the coating film.

Examples of the fluorine-containing polymer having no functional group and used for a top coat layer are PTFE, PFA, FEP, ETFE, PVdF and VdF copolymers.

As the primer for fluorine-containing coating composition, there can be used the above-mentioned fluorine-containing ethylenic polymer having functional group. In case where a substrate is coated with PTFE, it is preferable to use the primer selected from the reactive PTFE (I), reactive PFA and reactive FEP (II). It is particularly preferable to use, as the primer, thermo-melting reactive PFA or FEP (II) since it is possible to thermo-melt and strongly adhere to a substrate surface by sintering. In case where a substrate is coated with PFA or FEP, it is preferable to use, as the primer, reactive PFA or FEP (II). Further in case where a substrate is coated with ETFE, it is particularly preferable to use, as the primer, reactive ETFE (III) from the viewpoint of adhesion and transparency.

As a coating method using a primer layer, there can be used preferably a method of coating a fluorine-containing polymer, which mainly comprises the following three steps;

(First step) a step for applying, to a substrate surface, the primer for fluorine-containing coating composition comprising the above-mentioned fluorine-containing polymer having functional group,

(Second step) a step for applying a fluorine-containing coating composition comprising a fluorine-containing polymer having functional group or a fluorine-containing polymer having no functional group, to the primer layer formed in the above first step, and

(Third step) a step for sintering the laminated article obtained in the above first and second steps.

Further the primer layer applied in the above first step may be set by drying at 80° to 150° C. for about 5 minutes to about 30 minutes prior to the second step (2 coats/1 bake) or may be sintered, for example, at a high temperature of not less than the melting temperature thereof prior to the second step (2 coats/2 bakes).

The method for applying the primer in the first step is optionally selected depending on the form of the primer. For example, in case where the fluorine-containing primer is in the form of aqueous dispersion, spray coating, spin coating, brush coating and dip coating methods are used. Also in case of the form of powder coating composition, coating methods such as electrostatic coating, fluid-bed dip coating and rotolining are employed.

A thickness of the primer layer may vary depending on purpose, application, kind of a substrate surface and coating method. The thickness is from 1 to 50 μm, preferably from 2 to 20 μm. Since the thickness of the primer is in general thin as mentioned above, it is preferable to coat the primer in the form of aqueous dispersion by spray coating, etc.

The method for applying the coating composition comprising a fluorine-containing polymer having no functional group or a fluorine-containing polymer having functional group to the primer layer in the second step is optionally selected depending on kind of the fluorine-containing polymer, form of the coating, purpose and application. For example, in case of an aqueous dispersion and organic solvent dispersion, usually spray coating, brush coating, roll coating and spin coating are carried out. In case of a powder coating composition, electrostatic coating, fluid-bed dip coating and rotolining are carried out.

A coating thickness of the fluorine-containing polymer in this step varies entirely depending on application of the composite material having sliding property and coating method. The thickness is in general from 5 to 50 μm, preferably from about 10 μm to about 30 μm in case of spray coating. When a thick coating film is desired by using a powder coating composition, it is possible to apply at a thickness of 20 to 2,000 μm in case of electrostatic coating and at a thickness of 0.3 to 10 mm in case of rotolining.

Sintering conditions in the third step are optionally selected depending on kinds of fluorine-containing polymers (component, melting point, etc.) of the primer layer and the top layer thereon. The sintering is carried out in general at a temperature of not less than the melting point of the both fluorine-containing polymers. A sintering time varies depending on the sintering temperature, and is from five minutes to three hours, preferably from about 10 minutes to about 30 minutes. For example, when coating with PTFE, PFA and FEP, sintering is carried out at 320° to 400° C., preferably 350° to 400° C.

In order to enhance abrasion resistance of the composite material having sliding property of the present invention which is produced by applying a fluorine-containing polymer in the form of a coating composition to a substrate, a filler may be mixed to a coating film.

The coating film containing a filler is in general provided as an outermost layer, though it depends on application and processing method. Thus abrasion resistance of the composite material of the present invention is enhanced. Namely for example, when the composite material having sliding property is produced by applying, to a substrate, a coating composition such as a powder coating composition or an aqueous dispersion comprising the above-mentioned fluorine-containing polymer having functional group, it is possible to mix a filler to the powder coating composition or dispersion comprising the above-mentioned fluorine-containing polymer having functional group to give a coating film having improved abrasion resistance on the outermost layer.

Further for example, in case where a coating composition comprising the above-mentioned fluorine-containing polymer having functional group is used as a primer and thereon a coating composition comprising the fluorine-containing polymer having no functional group (PTFE, PFA, FEP, ETFE, etc.) is applied, it is possible to improve abrasion resistance by mixing a filler at least to the fluorine-containing polymer having no functional group for a top coat layer, applying it and forming a coating film.

As the filler to be mixed to the coating composition for the purpose to improve abrasion resistance, the same ones as mentioned above can be used.

Then technique for applying the above-mentioned fluorine-containing ethylenic polymer having functional group in the form of a film to produce composite materials having sliding property is explained.

Merits of applying in the form of a film are as follows.

{circle around (1)} A film comprising a fluorine-containing ethylenic polymer having functional group is advantageous from the viewpoint of processing since an applicator necessary for hot melt adhesive is not required, and the film can be adhered by thermocompression bonding while being put on a substrate or inserted between substrates.

{circle around (2)} Further since a uniform adhesive layer is formed on the whole surface of substrate, a film free from nonuniform adhesion and having uniform adhesive strength can be obtained, and thus can be also applied to a substrate having poor compatibility or no compatibility therewith.

{circle around (3)} Further the film can be cut into various shapes, and thus is advantageous from the viewpoint of a small loss in processing work, good working environment and cost.

The preferred fluorine-containing polymer film of the present invention is one which is produced by molding the above-mentioned fluorine-containing ethylenic polymer having functional group. The film can be adhered to various substrates without surface treating and using usual adhesives, thereby giving excellent characteristics of a fluorine-containing polymer to a substrate.

Though it is possible to produce adhesive films from the above-mentioned fluorine-containing polymers having functional group by using various adhesives depending on purpose of a composite material having sliding properties, film production process and adhering method, preferable is the above-mentioned copolymer (II) (reactive PFA or reactive FEP) or copolymer (III) (reactive ETFE) since the adhesive film itself has non-sticking property, heat resistance, chemical resistance and mechanical properties in addition to sliding properties; efficient film molding represented by melt-molding can be carried out; the film has good moldability; making the film thin and uniform is possible; and it is possible to melt the film by various thermocompression bonding methods to adhere strongly and beautifully to various substrates. Particularly preferred functional group is hydroxyl from the viewpoint of heat resistance.

A thickness of the fluorine-containing polymer film is selected depending on application of the composite material having sliding properties and is not limited particularly. The thickness is from 10 to 3,000 μm, preferably from 20 to 500 μm, particularly preferably from 40 to 300 μm.

In case of too thin films, special production method is required; it is difficult to handle the film at the time of adhering, and wrinkling, breaking and poor appearance occur easily; and there is a case where adhesive strength, mechanical strength, chemical resistance and weather resistance become insufficient. Too thick film is disadvantageous from the viewpoint of cost and workability at the time of bonding to one unit.

In the present invention, the fluorine-containing polymer film may be used alone or can be used in the laminated film comprising the film (adhesive layer) of fluorine-containing ethylenic polymer having functional group and the film (surface layer) of fluorine-containing ethylenic polymer having no functional group.

Namely one surface of the film is a layer comprising a fluorine-containing ethylenic polymer having functional group and has adhesive property to a substrate, and another surface of the film is a layer comprising usual fluorine-containing polymer. By bringing the surface of the fluorine-containing ethylenic polymer having functional group into contact to the substrate and adhering it to the substrate by thermocompression bonding, etc., excellent characteristics of the fluorine-containing polymer such as sliding property, non-sticking property, friction resistance, weather resistance, chemical resistance and electrical properties (high frequency electric insulating property) can be given to the composite material.

In the present invention, a thickness of the two-layered laminated film of fluorine-containing polymer is selected depending on application of the composite material having sliding property, and is not limited particularly. The total thickness of two layers is from 20 to 5,000 μm, preferably from 40 to 1,000 μm, particularly preferably from 100 to 500 μm.

A thickness of each layer which can be used is from 5 to 1,000 μm, preferably from 10 to 500 μm, particularly preferably from 10 to 200 μm of the adhesive layer, and from about 15 μm to about 4,995 μm, preferably from 30 to 990 μm, particularly preferably from 90 to 490 μm of the fluorine-containing polymer layer (surface layer).

The film for the surface layer may be adhered after adhering the film for the adhesive layer to a substrate.

To the film of fluorine-containing polymer having functional group can be optionally incorporated proper additives such as a reinforcing agent, filler, stabilizer, ultraviolet ray absorber, pigment, etc. in an amount not lowering characteristics of the film. Those additives make it possible to improve thermal stability, surface hardness, abrasion resistance, weather resistance and electrostatic charge, etc.

The fluorine-containing polymer film of the present invention can be produced, depending on kind of polymers used and desired shape of the film, by various methods such as thermal melting method, extrusion method, cutting method and solvent-casting method and a method of applying a powder or an aqueous dispersion or organic solvent dispersion to form a continuous coating film.

For example, a polymer which comprises the above-mentioned reactive PTFE and is difficult to be melt-molded can be molded by compression molding, extrusion molding (ram extrusion, paste extrusion, roll press, etc.) or the like. A polymer such as reactive PFA, FEP or ETFE which is melt-moldable is molded by compression molding and extrusion molding, and melt-extrusion molding is particularly preferred from the viewpoint of productivity and product quality.

Bonding of the two films into one laminated film can be carried out by a method of overlapping the respective molded films for adhesive layer and surface layer and then compression-molding; a method of applying one fluorine-containing polymer to a molded film comprising another fluorine-containing polymer; a method of carrying out film molding and bonding of films at the same time through multi-layer co-extrusion molding method, or the like method. Among them, the multi-layer co-extrusion molding method is preferred from the viewpoint of productivity and product quality.

Adhesion of the film of fluorine-containing polymer having functional group to a substrate is achieved through thermal activation by heating, etc. Further thermo-melting adhesion is preferable. Represented examples of the adhering method are heating roller method and heat press method. Also there are other methods such as high-frequency heating, microwave heating, vacuum compression (vacuum press, etc.) and pneumatic press. Those methods can be optionally selected depending on kind and shape of a substrate, condition and kind of film, etc.

The composite material having sliding property of the present invention which is obtained by applying the fluorine-containing polymer in the form of a film to a substrate may have a layer containing a filler particularly to enhance abrasion resistance. The layer containing a filler is in general provided on an outermost surface though it depends on application and processing method. Thus abrasion resistance of the composite material of the present invention is improved more.

Namely for example, in case where a film comprising the above-mentioned fluorine-containing polymer having functional group is applied solely, by mixing a filler to the film of fluorine-containing polymer having functional group and applying the film to a substrate, abrasion resistance can be improved. Also for example, in case where a composite material having sliding property is produced by using a film comprising the fluorine-containing polymer having functional group as an adhesive layer and further laminating thereon a film or sheet of fluorine-containing polymer having no functional group (PTFE, PFA, FEP, ETFE, etc.), it is possible to obtain the composite material having further improved abrasion resistance at least by mixing a filler to the film of fluorine-containing polymer having no functional group of a surface layer and laminating the film on the adhesive layer.

As the filler mixed to the film to improve abrasion resistance, the same ones as mentioned above can be used.

Examples of the substrate on which the above-mentioned fluorine-containing ethylenic polymer having functional group can be adhered, are a metallic substrate, ceramic substrate, synthetic resin substrate, and the like.

Metals of the metallic substrate encompass metal, alloys of two or more metals, metal oxide, metal hydroxide, metal salts such as carbonate and sulfate, etc. Among them, metal, metal oxide and alloys are more preferable from the viewpoint of adhesive property.

Examples of the metallic substrate are metals and metal compounds of aluminum, iron, nickel, titanium, molybdenum, magnesium, manganese, copper, silver, lead, tin, chromium, beryllium, tungsten and cobalt, alloys of two or more thereof, etc.

Examples of the alloys are alloy steels such as carbon steel, Ni steel, Cr steel, Ni—Cr steel, Cr—Mo steel, stainless steel, silicon steel and permalloy; aluminum alloys such as Al—Cl, Al—Mg, Al—Si, Al—Cu—Ni—Mg and Al—Si—Cu—Ni—Mg; copper alloys such as brass, bronze, silicon bronze, silicon brass, nickel silver and nickel bronze; nickel alloys such as nickel manganese (D nickel), nickel-aluminum (Z nickel), nickel-silicon, Monel metal, Constantan, nichrome Inconel and Hastelloy; and the like.

Further as the aluminum-based metal, there can be used pure aluminum; aluminum oxide; and aluminum alloys for casting and expanding such as Al—Cu, Al—Si, Al—Mg, Al—Cu—Ni—Mg, Al—Si—Cu—Ni—Mg alloys, high tensile aluminum alloy and corrosion resistant aluminum alloy.

Also as the iron-based metals, there can be used pure iron, iron oxide, carbon steel, Ni steel, Cr steel, Ni—Cr steel, Cr—Mo steel, Ni—Cr—Mo steel, stainless steel, silicon steel, permalloy, non-magnetic steel, magnet steel, cast iron, etc.

Also the fluorine-containing ethylenic polymer having functional group can be adhered to a substrate which was subjected to, for the purpose of preventing corrosion of metal, coating of other metal by electroplating, hot dipping, chromatizing, siliconizing, colorizing, sheradizing, metal spraying, etc.; forming a phosphate film by phosphatization; forming metal oxide by anodizing or heat-oxidizing; or electrochemical corrosion prevention.

Further for the purpose of enhancing adhesion, the surface of metallic substrate may be subjected to chemical preparation with a phosphoric acid, sulfuric acid, chromic acid, oxalic acid, etc., or may be subjected to surface roughening by sand blasting, shot blasting, grit blasting, honing, paper scratching, wire scratching, hair line finishing, etc. For the purpose of exhibiting clear surface pattern of the substrate, the metal surface may be subjected to coloring, printing, etching, etc.

In case of the above-mentioned aluminum or aluminum alloy substrate, in order to enhance corrosion resistance, surface hardness and adhesive property of the substrate, it is possible to form an oxide film (alumite) on the substrate by anodizing with caustic soda, oxalic acid, sulfuric acid or chromic acid and also use the aluminum or aluminum alloy substrate subjected to other surface treatments mentioned above.

Further there may be used a substrate plated, on its surface, with other metal as mentioned above, for example, steel plate subjected to hot-dip zinc-plating, hot-dip zinc alloy plating, aluminum plating, zinc-nickel plating, zinc-aluminum plating, or the like; a substrate coated with other metal by diffusion coating or thermal spraying; a substrate, on which an oxide film is formed by chemical conversion treatment with chromic acid or phosphoric acid or heat-treatment; a substrate subjected to electric corrosion preventing treatment (for example, galvanized steel plate); or the like.

Examples of the ceramic substrate are, for instance, glass, pottery, porcelain, etc.

Components of glass are not particularly limited. Examples are silica glass, lead glass, non-alkali glass, alkali glass, etc.

Examples of the synthetic resin substrate are, for instance, an acrylic resin, polycarbonate, polypropylene, heat resistant engineering plastic, thermosetting resin etc.

Examples of the substrate used usually for the composite material having sliding property of the present invention are all of those mentioned above, and as metallic substrates which are used in many cases are, for instance,

{circle around (1)} cold rolled steel sheet,

{circle around (2)} plated steel sheet, for example, Zn-plated steel sheet, Zn alloy-plated steel sheet, Al-plated steel sheet, Al alloy-plated steel sheet, Cr-plated steel sheet (TFS), Ni-plated steel sheet, Cu-plated steel sheet, galvanized steel sheet, etc.,

{circle around (3)} aluminum sheet,

{circle around (4)} titanium sheet,

{circle around (5)} stainless steel sheet, and the like.

In addition, where transparency is required, a ceramic substrate of glass and a synthetic resin substrate of acrylic resin and polycarbonate are usually used.

It is preferable that the form of the substrate is the same as a form of a finished product using the composite material having sliding property from the viewpoint that there is a case where processability is difficult after a coating film, etc. is formed.

It is preferable that the fluorine-containing polymer having functional group which is used for the composite material having sliding property of the present invention is in the form of laminated article since it has good adhesion to metal and glass. Examples of the particularly preferred laminated article for sliding application are as follows.

{circle around (1)} A laminated article comprising:

a) metal substrate of aluminum, stainless steel, or the like,

b) layer of reactive PFA, reactive FEP or reactive PTFE and

c) layer of PTFE or PFA containing 1 to 40% by weight of carbon fiber which is characterized in that the layer b) forms an adhesive layer between a) and c) and is preferably used for applications such as bearing, mechanical seal and bearing pad from the viewpoint of excellent abrasion resistance, property of withstanding load and post-processability such as bending.

{circle around (2)} A laminated article comprising:

a) metal substrate of aluminum, stainless steel, or the like,

b) layer of reactive PFA, reactive FEP or reactive PTFE and

c) layer of PTFE or PFA containing 1 to 30% by weight of glass fiber which is characterized in that the layer b) forms an adhesive layer between a) and c) and is preferably used for applications such as bearing, gasket and valve disc from the viewpoint of abrasion resistance.

{circle around (3)} A laminated article comprising:

a) metal substrate of aluminum, stainless steel, or the like,

b) layer of reactive PFA, reactive FEP or reactive PTFE and

c) layer of PTFE or PFA containing 5 to 40% by weight of graphite which is characterized in that the layer b) forms an adhesive layer between a) and c) and is preferred from the viewpoint of low initial abrasion and friction coefficient, good cold flow, excellent heat conductivity and excellent chemical resistance.

{circle around (4)} A laminated article comprising:

a) metal substrate of aluminum, stainless steel, or the like,

b) layer of reactive PFA, reactive FEP or reactive PTFE and

c) layer of PTFE or PFA containing 10 to 80% by weight of bronze which is characterized in that the layer b) forms an adhesive layer between a) and c), is preferred from the viewpoint of high hardness and excellent compression strength and heat conductivity and is suitable for building applications such as bridge beam support and gate bearing.

{circle around (5)} A laminated article comprising:

a) metal substrate of aluminum, stainless steel, or the like,

b) layer of reactive PFA, reactive FEP or reactive PTFE and

c) layer of PTFE or PFA containing 1 to 40% by weight of aromatic polyesters (all aromatic polyesters particularly having high melting point and being non-melting) which is characterized in that the layer b) forms an adhesive layer between a) and c), is preferred from the point that a counterpart article contacting the composite material is hard to be injured even if the counterpart is a soft metal, and is suitable for bearing of soft metal.

{circle around (6)} A laminated article comprising:

a) metal substrate of aluminum, stainless steel, or the like,

b) layer of reactive PFA, reactive FEP or reactive PTFE and

c) layer of PTFE or PFA containing 5 to 30% by weight of glass fiber and 1 to 10% by weight of graphite which is characterized in that the layer b) forms an adhesive layer between a) and c), is preferred from the viewpoint of excellent abrasion resistance and cold flow and is suitable for piston ring, etc.

{circle around (7)} A laminated article comprising:

a) metal substrate of aluminum, stainless steel, or the like,

b) layer of reactive PFA, reactive FEP or reactive PTFE and

c) layer of PTFE or PFA containing 5 to 30% by weight of glass fiber and 1 to 10% by weight of molybdenum disulfide which is characterized in that the layer b) forms an adhesive layer between a) and c), is preferred from the viewpoint of excellent abrasion resistance and cold flow, high tensile strength, a large expansion and good electric insulating property and is suitable for tape liner type bearing, etc.

Hitherto a laminated article produced by applying, to metal, a fluorine-containing resin only or a composition comprising a fluorine-containing resin and a filler has been insufficient in mechanical properties, creep resistance and abrasion resistance. On the contrary, the composite materials having sliding property of above {circle around (1)} to {circle around (7)} laminated articles are preferred from the point that mechanical strength thereof can be improved and they can be applied to large size sliding parts. Further the composite materials having sliding property of above {circle around (1)} to {circle around (7)} laminated articles are preferred since they can easily give sliding property to a metal surface depending on application, purpose and a counterpart article.

The composite material of the present invention can be used on various machine, appliances and materials firstly because the fluorine-containing polymer having functional group on the surface of the composite material has excellent sliding property, secondarily because the fluorine-containing polymer having functional group is adhered to a substrate with good adhesive strength and thirdly because the fluorine-containing polymer having functional group has good non-sticking property, stain-proofing property, transparency (property for exhibiting clear surface pattern), heat resistance, water- and oil-repellency and the like.

Equipment, appliances, members and parts, to which the composite material having sliding property of the present invention can be applied suitably are classified by fields they belong to and raised below, but the present invention is not limited to them.

[1] Office Automation-related Equipment

With respect to office automation-related equipment, as a paper feeding speed has been made higher, there are a lot of parts requiring sliding property. Mentioned below are non-restricted represented examples thereof.

{circle around (1)} Separating Claw and Fixing Bearing (Surface)

Substrate: Heat resistant resin-made substrate (for example, polyphenylene sulfide, polyamide imide, polyether imide, polyoxymethylene (POM), polyether ether ketone (PEEK) or the like)

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating

When the composite material of the present invention is used, a separating claw being capable of preventing staining by toner, having excellent abrasion resistance, assuring easy paper feeding and hardly injuring a roller and a fixing bearing having excellent friction resistance, abrasion resistance and heat resistance can be obtained. Since the fluorine-containing polymer having functional group itself has excellent adhesive property, no primer need be provided, and processability in production is excellent.

{circle around (2)} Paper Delivery Roller and Paper Delivery Guide

Substrate: Resin-made substrate (for example, polyphenylene sulfide, polyamide imide, polyether imide, POM, PEEK, or the like)

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating

When the composite material of the present invention is used, a paper delivery roller and paper delivery guide being capable of preventing staining by toner and having excellent abrasion resistance can be obtained. Since the fluorine-containing polymer having functional group itself has excellent adhesive property, no primer need be provided, and processability in production is excellent.

[2] Domestic Appliances

With respect to domestic appliances, there are portions (parts) requiring sliding properties including abrasion resistance. Examples thereof are raised below together with effects to be exhibited in addition to sliding properties. The present invention also relates to those parts and appliances.

{circle around (1)} Iron

Application: Heating surface

Substrate: SUS and steel plate

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA

Form of polymer to be applied: Coating and film

In this application, heat resistance, processability and property for exhibiting clear surface pattern which the composite material of the present invention possesses can be used particularly effectively.

[3] Housing Facilities and Equipment

With respect to housing facilities and equipment, there are portions (parts) requiring sliding properties including abrasion resistance and friction resistance from the viewpoint of easy handling. Examples thereof are raised below together with effects to be exhibited in addition to sliding properties. The present invention also relates to those housing facilities and equipment and portions (parts) thereof.

{circle around (1)} Escalator

Application: Surface of skirt board (prevention of being caught in a machine)

Substrate: SUS and steel plate

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating and film

In these applications, processability, property for exhibiting clear surface pattern and weather resistance which the composite material of the present invention possesses can be used particularly effectively.

[4] Cars

Cars have many portions (parts) requiring heat resistance and chemical resistance, such as engine and gear.

{circle around (1)} Rotary Engine

Application: Inner surface

Substrate: Aluminum or steel plate

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating

In these applications, processability, heat resistance, non-sticking property and stain-proofing property which the composite material of the present invention possesses can be used particularly effectively.

{circle around (2)} Piston and Piston Ring

Application: Surface

Substrate: Aluminum or steel plate

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating

In these applications, processability and heat resistance which the composite material of the present invention possesses can be used particularly effectively.

{circle around (3)} Throttle Shaft

Application: Surface

Substrate: Aluminum or iron-based metal

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating

In these applications, processability and heat resistance which the composite material of the present invention possesses can be used particularly effectively.

In addition, sliding property can be given to steering parts, hinged pin, various gears, brake shoe and bearing retainer by applying the polymer in the form of coating to surfaces thereof.

[5] Construction and Building Materials

The composite material can be used on movable supports such as stanchion and base of large size buildings, bridges and the like, particularly for applications requiring sliding property for transfer at high load at low speed.

{circle around (1)} Foundation of Elevated Road Bridge, other Bridges and the like

Application: Bearing pad

Substrate: Iron

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating and film

In these applications, a laminated article of metal has excellent durability particularly against high load, and friction resistance and abrasion resistance can be used more effectively.

{circle around (2)} Application for Isolation System for House and Building

Application: Guiding portions of foundation and stanchion

Substrate: Iron or stainless steel

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating or film

In these applications, the composite material are excellent in sliding property and durability against transfer (vibration) at high load at low speed, and can be used more effectively for isolation system particularly against earthquake and strong wind.

{circle around (3)} Support for Pipes of Plant

Application: Contact surface to supporting pipe

Substrate: Iron and stainless steel

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating or film

In these applications, the support can be used preferably for fixing metal pipe from the viewpoint of expansion and shrinkage of the pipe due to change in air temperature and temperature of a flowing substance.

[6] Others

{circle around (1)} Bolt and Nut

Application: surface

Substrate: Iron

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating

In these applications, processability, rust-preventing property, chemical resistance and low torque property which the composite material of the present invention possesses can be used particularly effectively.

{circle around (2)} Cutlery such as Scissors, saw and Kitchen Knife

Application: Surface of blade

Substrate: Iron

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating

In these applications, non-sticking property, stain-proofing property, processability and cutting ability at low load which the composite material of the present invention possesses can be used particularly effectively.

{circle around (3)} Parts for Pump

Application: Inner surface and outer surface of plunger and surface of gear

Substrate: Aluminum and iron

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating or film

In these applications, chemical resistance, processability and abrasion resistance which the composite material of the present invention possesses can be used particularly effectively.

{circle around (4)} Parts for Air Conditioner (Air Conditioners for Car, Room, etc.)

Application: Piston ring

Substrate: Aluminum and iron

Fluorine-containing polymer having functional group: Reactive PTFE or reactive PFA or FEP

Form of polymer to be applied: Coating

In these applications, processability and chemical resistance which the composite material of the present invention possesses can be used particularly effectively.

In addition, the composite material of the present invention can be used for parts of vending machine, camera, medical machine (gastrocamera), clock, agricultural machine and oil-less bearing for mechanical industry.

EXAMPLE

The composite material having sliding property of the present invention is then explained by means of preparation examples and examples, but the present invention is not limited to those examples.

Preparation Example 1

(Preparation of Aqueous Dispersion Comprising PFA having Hydroxyl)

A 3-liter glass-lined autoclave equipped with a stirrer, valve, pressure gauge and thermometer was charged with 1,500 ml of pure water and 9.0 g of ammonium perfluorooctanoate. After replacing with nitrogen gas sufficiently, the autoclave was evacuated and charged with 20 ml of ethane gas.

Then 3.8 g of perfluoro-(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol) (formula (7)):

and 18 g of perfluoro(propyl vinyl ether) (PPVE) were fed into the autoclave with pressurized nitrogen gas, and a temperature inside the system was maintained at 70° C.

Pressurized tetrafluoroethylene (TFE) gas was introduced into the autoclave with stirring so that the inside pressure of the autoclave became 8.5 kgf/cm²G.

Then a solution prepared by dissolving 0.15 g of ammonium persulfate in 5.0 g of water was added with pressurized nitrogen gas to initiate the reaction.

Since the pressure lowered with the advance of the polymerization reaction, it was increased again to 8.5 kgf/cm² by feeding tetrafluoroethylene gas at the time when it lowered to 7.5 kgf/cm²G. Thus the decreasing and increasing of the pressure were repeated.

With continuing supply of tetrafluoroethylene, every time when about 40 g of tetrafluoroethylene gas was consumed after starting of the polymerization, 1.9 g of the above-mentioned fluorine-containing ethylenic monomer having hydroxyl (compound represented by the formula (7)) was introduced under pressure three times (5.7 g in total) to continue the polymerization. At the time when about 160 g of tetrafluoroethylene gas was consumed after starting of the polymerization, the supplying thereof was terminated and the autoclave was cooled and the un-reacted monomer was released to give 1,702 g of a bluish semi-transparent aqueous dispersion.

A concentration of the polymer in the obtained aqueous dispersion was 10.9%, and a particle size measured by dynamic light scattering method was 70.7 nm.

Also a part of the obtained aqueous dispersion was sampled and subjected to freeze coagulation, and the precipitated polymer was rinsed and dried to isolate a white solid. Components and their amounts of the obtained copolymer which were determined through ¹⁹F-NMR and IR analyses were TFE/PPVE/(Fluorine-containing ethylenic monomer having hydroxyl and represented by the formula (7))=97.7/1.2/1.1% by mole.

In infrared spectrum, characteristic absorption of —OH was observed at 3,620 to 3,400 cm⁻¹.

According to DSC analysis, Tm was 310° C., and according to DTGA analysis, 1% thermal decomposition temperature Td was 368° C. A melt flow rate measured under conditions of preheating at 372° C. for five minutes at a load of 7 kgf/cm² by using Koka-type flow tester and nozzles of 2 mm diameter×8 mm length was 12.0 g/10 min.

Preparation Example 2

(Preparation of Aqueous Dispersion Comprising PFA having Hydroxyl)

The same autoclave as in Preparation Example 1 was charged with 1,500 ml of pure water and 9.0 g of ammonium perfluorooctanoate. After replacing with nitrogen gas sufficiently, the autoclave was evacuated and charged with 20 ml of ethane gas.

Then 1.9 g of perfluoro-(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol) (compound of the formula (7)) and 16.1 g of perfluoro(propyl vinyl ether) (PPVE) were fed into the autoclave with pressurized nitrogen gas, and a temperature inside the system was maintained at 70° C.

Pressurized tetrafluoroethylene (TFE) gas was introduced into the autoclave with stirring so that the inside pressure became 8.5 kgf/cm²G.

Then a solution prepared by dissolving 0.15 g of ammonium persulfate in 5.0 g of water was fed with pressurized nitrogen gas to initiate the reaction.

Since the pressure lowered with the advance of the polymerization reaction, at the time when the pressure lowered down to 7.5 kgf/cm²G, it was increased again to 8.5 kgf/cm²G with tetrafluoroethylene gas, and the decreasing and increasing of the pressure were repeated.

With continuing supply of tetrafluoroethylene, every time when 40 g of tetrafluoroethylene gas was consumed after starting of the polymerization, 0.95 g of the fluorine-containing ethylenic monomer having hydroxyl (compound represented by the formula (7)) was introduced three times (2.85 g in total) under pressure to continue the polymerization. When 160 g of tetrafluoroethylene was consumed after starting of the polymerization, the supplying thereof was terminated. The autoclave was cooled and the un-reacted monomer was released to give 1,692 g of an aqueous dispersion. A concentration of the polymer in the obtained aqueous dispersion was 10.6% and a particle size thereof was 76.8 nm.

A part of the aqueous dispersion was sampled, and a white solid was isolated in the same manner as in Preparation Example 1.

The same analysis as above of the obtained white solid indicates:

TFE/PPVE/(Fluorine-containing monomer having hydroxyl and represented by the formula (7))=98.3/1.1/0.6% by mole

Tm=310° C.

1% Thermal decomposition temperature Td=374° C.

Melt flow rate: 9.5 g/10 min

In infrared spectrum, characteristic absorption of —OH was observed at 3,620 to 3,400 cm⁻¹.

Preparation Example 3

(Synthesis of Aqueous Dispersion of PFA having no Functional Group)

Emulsion polymerization was carried out in the same manner as in Preparation Example 1 except that perfluoro-(1,1,9,9-tetrahydro-2,5-bistrifiluoromethyl-3,6-dioxa-8-nonenol) (compound of the formula (7)) was not used, and 1,662 g of an aqueous dispersion of PFA having no functional group was obtained.

A concentration of the polymer in the aqueous dispersion was 9.7%, and a particle size thereof was 115 nm.

A white solid was isolated and analyzed in the same manner as in Preparation Example 1.

TFE/PPVE=98.9/1.1% by mole

Tm=310° C.

1% Thermal decomposition temperature Td=479° C.

Melt flow rate: 19.2 g/10 min

In infrared spectrum, no characteristic absorption of —OH was observed.

Preparation Example 4

(Synthesis of PFA having Hydroxyl)

A 6-liter glass-lined autoclave equipped with a stirrer, valve, pressure gauge and thermometer was charged with 1,500 ml of pure water. After replacing with nitrogen gas sufficiently, the autoclave was evacuated and charged with 1,500 g of 1,2-dichloro-1,1,2,2-tetrafluoroethane (R-114).

Then 5.0 g of perfluoro-(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol) (compound of the formula (7)), 130 g of perfluoro(propyl vinyl ether) (PPVE) and 180 g of methanol were fed into the autoclave with pressurized nitrogen gas, and a temperature inside the system was maintained at 35° C.

Pressurized tetrafluoroethylene (TFE) gas was introduced into the autoclave with stirring so that the inside pressure became 8.0 kgf/cm²G. Then 0.5 g of a 50% methanol solution of di-n-propyl peroxydicarbonate was fed with pressurized nitrogen to initiate the reaction.

Since the pressure lowered with the advance of the polymerization reaction, at the time when the pressure lowered down to 7.5 kgf/cm²G, it was increased again to 8.0 kgf/cm² by feeding tetrafluoroethylene gas, and the decreasing and increasing of the pressure were repeated.

With continuing supply of tetrafluoroethylene, every time when about 60 g of tetrafluoroethylene gas was consumed after starting of the polymerization, 2.5 g of the fluorine-containing ethylenic monomer having hydroxyl (compound represented by the formula (7)) was introduced nine times (22.5 g in total) under pressure to continue the polymerization. When about 600 g of tetrafluoroethylene was consumed after starting of the polymerization, the supplying thereof was terminated. The autoclave was cooled and the un-reacted monomer and R-114 were released.

The obtained copolymer was washed with water, rinsed with methanol and then vacuum-dried to give 710 g of a white solid. The composition of the obtained copolymer was TFE/PPVE/(Fluorine-containing ethylenic monomer having hydroxyl and represented by the formula (7))=97.0/2.0/1.0% by mole according to ¹⁹F-NMR and IR analyses. In infrared spectrum, characteristic absorption of —OH was observed at 3,620 to 3,400 cm⁻¹. According to DSC analysis, Tm was 305° C., and according to DTGA analysis, 1% thermal decomposition temperature Td was 375° C. A melt flow rate measured under conditions of preheating at 372° C. for five minutes at a load of 7 kgf/cm² by using Koka-type flow tester and nozzles of 2 mm diameter×8 mm length was 32 g/10 min.

Preparation Example 5

(Synthesis of PFA having Hydroxyl)

A 6-liter glass-lined autoclave equipped with a stirrer, valve, pressure gauge and thermometer was charged with 1,500 ml of pure water. After replacing with nitrogen gas sufficiently, the autoclave was evacuated and charged with 1,500 g of 1,2-dichloro-1,1,2,2-tetrafluoroethane (R-114).

Then the reaction was initiated in the same manner as in Preparation Example 4 except that 2.5 g of perfluoro-(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol) (formula (7)), 132 g of perfluoro(propyl vinyl ether) (PPVE) and 230 g of methanol were used. A temperature inside the system was maintained at 35° C.

Pressurized tetrafluoroethylene (TFE) gas was introduced into the autoclave with stirring so that the inside pressure of the autoclave became 8.0 kgf/cm²G. Then 0.5 g of a 50% methanol solution of di-n-propyl peroxydicarbonate was added with pressurized nitrogen gas to initiate the reaction.

Since the pressure lowered with the advance of the polymerization reaction, it was increased again to 8.0 kgf/cm² by feeding tetrafluoroethylene gas at the time when it lowered to 7.5 kgf/cm²G. Thus the decreasing and increasing of the pressure were repeated.

Further 680 g of a white solid copolymer was obtained in the same manner as in Preparation Example 4 except that every time when about 60 g of tetrafluoroethylene gas was consumed after starting of the polymerization, 1.23 g of the above-mentioned fluorine-containing ethylenic monomer having hydroxyl (compound represented by the formula (7)) was introduced under pressure nine times (11.10 g in total). Components and their amounts of the obtained copolymer which were determined through ¹⁹F-NMR and IR analyses were TFE/PPVE/(Fluorine-containing ethylenic monomer having hydroxyl and represented by the formula (7))=97.6/2.0/0.4% by mole. In infrared spectrum, characteristic absorption of —OH was observed at 3,620 to 3,400 cm⁻¹. According to DSC analysis, Tm was 310° C., and according to DTGA analysis, a decomposition starting temperature was 368° C. and 1% thermal decomposition temperature Td was 375° C. A melt flow rate measured under conditions of preheating at 372° C. for five minutes at a load of 7 kgf/cm² by using Koka-type flow tester and nozzles of 2 mm diameter×8 mm length was 42 g/10 min.

Preparation Example 6

(Synthesis of PFA having no Functional Group)

Synthesis was carried out in the same manner as in Preparation Example 4 except that perfluoro-(1,1,9,9-tetrahydro-2,5-bistrifluoromethyl-3,6-dioxa-8-nonenol) (compound represented by the formula (7)) was not used and 240 g of methanol was used, and thus 597 g of PFA having no functional group was obtained.

The obtained PFA was analyzed in the same manner as in Preparation Example 4 and the results were as follows.

TFE/PPVE=98.2/1.8% by mole

Tm=310° C.

Td=469° C. (1% weight reduction)

Melt flow rate: 24 g/10 min

Preparation Example 7

(Preparation of PFA Powder Coating Composition having Hydroxyl)

The PFA powder having hydroxyl (apparent specific gravity: 0.5, true specific gravity: 2.1, average particle size: 600 μm) and prepared in Preparation Example 4 was compressed into a sheet of 60 mm wide×5 mm thick by a Roller Compactor (Model BCS-25 available from Shinto Kogyo Kabushiki Kaisha), and then crushed into about 10 mm diameter by a crusher and further finely pulverized at room temperature at 11,000 rpm by a pulverizer (Cosmomizer Model N-1 available from Kabushiki Kaisha Nara Kikai Seisakusho). Subsequently the coarse powder particles of not less than 170 mesh (88 μm of sieve opening) were separated by a classifier (Hibolder Model 300SD available from Shi-Tokyo Kikai Kabushiki Kaisha) to give a PFA powder coating composition having hydroxyl. An apparent density of the powder was 0.7 g/ml, and an average particle size thereof was 20 μm.

Preparation Example 8

(Preparation of PFA Powder Coating Composition having no Functional Group)

A PFA powder coating composition was prepared in the same manner as in Preparation Example 7 except that the PFA powder having no functional group (apparent specific gravity: 0.6, true specific gravity: 2.1, average particle size: 400 μm) and prepared in Preparation Example 6 was used instead of the PFA powder having hydroxyl and prepared in Preparation Example 4. An apparent density of the powder was 0.73 g/ml, and an average particle size thereof was 20 μm.

Preparation Example 9

(Synthesis of Fluorine-containing Polymer Prepared by using a Non-fluorine-containing Monomer having Functional Group)

A 1-liter stainless steel autoclave equipped with a stirrer, valve, pressure gauge and thermometer was charged with 250 g of butyl acetate, 36.4 g of vinyl pivalate (VPi) and as a non-fluorine-containing monomer having hydroxyl, 32.5 g of 4-hydroxybutyl vinyl ether (HBVE) and 4.0 g of isopropoxycarbonyl peroxide. After cooling to 0° C. with ice and replacing with nitrogen gas sufficiently, the autoclave was evacuated and charged with 47.5 g of isobutylene (IB) and 142 g of tetrafluoroethylene (TFE).

The autoclave was heated to 40° C. and reaction was carried out for 30 hours with stirring. At the time when the inside pressure of the reaction vessel was lowered to not more than 2.0 kg/cm², the reaction was terminated. The autoclave was cooled and un-reacted gas monomer was released, and thus a butyl acetate solution of a fluorine-containing polymer was obtained. A polymer concentration was 45%.

A fluorine-containing polymer was separated from the obtained butyl acetate solution of a fluorine-containing polymer through re-precipitation method, followed by sufficiently reducing pressure and drying, thus being separated in the form of white solid. According to ¹H-NMR and ¹⁹F-NMR elementary analyses, the obtained fluorine-containing polymer was a copolymer of TFE/IB/VPi/HBVE=44/34/15/7% by mole.

Preparation Example 10

(Production of Film of PFA having Hydroxyl)

A metal die of 100 mm diameter was charged with 8.0 g of the white solid obtained in Preparation Example 4 and set on a press machine of 350° C., followed by preheating for 30 minutes and then compression-molding at 70 kg/cm² for one minute. Thus a 0.5 mm thick film was obtained.

Preparation Example 11

(Production of Film of PFA having Hydroxyl)

The same procedures as in Preparation Example 10 were repeated except that the white solid obtained in Preparation Example 5 was used, to give a 0.5 mm thick film.

Preparation Example 12

(Production of Film of PFA having no Functional Group)

The same procedures as in Preparation Example 10 were repeated except that the white solid obtained in Preparation Example 6 was used, to give a 0.5 mm thick film.

Preparation Example 13

(Production of Film of PFA having Hydroxyl by Extrusion)

The white solid obtained in Preparation Example 4 was extruded at 350° to 370° C. by using a two screw extruder (LABOPLASTOMIL available from Toyo Seiki Kabushiki Kaisha) to give pellets. The pellets were extruded at 360° to 380° C. at a roll temperature of 120° C. by using a single screw extruder (LABOPLASTOMIL available from Toyo Seiki Kabushiki Kaisha) to give a film of 10 cm wide×100 to 150 μm thick.

Preparation Example 14

(Production of Film of PFA having no Functional Group by Extrusion)

The same procedures as in Preparation Example 13 were repeated except that the white solid obtained in Preparation Example 6 was used, to give pellets. Further extrusion was carried out in the same manner as in Preparation Example 13 to give a film of 10 cm wide×100 to 150 μm thick.

Preparation Example 15

(Production of Laminated Film of PFA having Hydroxyl and PTFE)

The film of PFA having hydroxyl and obtained in Preparation Example 13 and a 0.5 mm thick PTFE film were overlapped and compression-molded in the same manner as in Preparation Example 10.

The two layers were adhered strongly.

Example 1

(1) Pre-treatment of Substrate

A 1.5 mm thick pure aluminum plate (A1050P) and a 1.5 mm thick SUS304 plate were degreased respectively with acetone.

(2) Formation of Primer Layer Comprising Fluorine-containing Polymer having Functional Group

An aqueous dispersion comprising PFA having hydroxyl and prepared in Preparation Example 1 was applied to the plate by an air spray so that a coating thickness would become about 5 μm, followed by infrared-drying at 90° C. for 10 minutes and sintering at 380° C. for 20 minutes.

(3) Formation of Layer (Top Layer) Comprising Fluorine-containing Polymer having no Functional Group

Onto the primer layer obtained in (2) above was applied an aqueous coating composition of PTFE (POLYFLON TFE Enamel EK4300CRN available from DAIKIN INDUSTRIES, LTD.) as a coating composition of fluorine-containing polymer having no functional group by an air spray so that a coating thickness would become about 20 μm, followed by infrared-drying at 90° C. for 10 minutes and sintering at 380° C. for 20 minutes.

(4) Evaluation of Adhesive Property

The method of evaluation is as follows.

(Cross-cut Adhesion Test)

According to JIS K 5400 1990, 8.5.2, a coated surface was cross-cut to give 100 squares, and an adhesive tape (available from Nichiban Kabushiki Kaisha) was adhered to the cross-cut surface sufficiently. Then immediately the tape was torn off. This was repeated 10 times with new adhesive tapes to check to see how many squares remain among 100 squares. The results are shown in Table 1.

Example 2

A coated plate was produced in the same manner as in Example 1 except that a primer layer was formed by using the aqueous dispersion comprising PFA having hydroxyl and obtained in Preparation Example 2 as a primer comprising a fluorine-containing polymer having functional group. The evaluation for adhesive property was carried out, and the results are shown in Table 1.

TABLE 1 Com. Com. Com. Ex. 1 Ex. 2 Ex. 1 Ex. 3 Ex. 4 Ex. 2 Ex. 5 Ex. 6 Ex. 3 Fluorine-containing Prep. Prep. Prep. Prep. Prep. Prep. Prep. Prep. Prep. aqueous dispersion Ex. 1 Ex. 2 Ex. 3 Ex. 1 Ex. 2 Ex. 3 Ex. 1 Ex. 2 Ex. 3 used for primer layer Fluorine-containing PTFE PTFE PTFE FEP FEP FEP PFA PFA PFA resin forming top layer Evaluation of adhesion (Cross-cut adhesion test) SUS304 100/100 100/100 0/100 100/100 100/100  0/100 100/100 100/100 20/100 Pure aluminum 100/100 100/100 0/100 100/100 100/100 20/100 100/100 100/100 30/100

Comparative Example 1

A coated plate was produced in the same manner as in Example 1 except that a primer layer was formed by using the aqueous dispersion comprising PFA having no functional group and obtained in Preparation Example 3 instead of a primer comprising a fluorine-containing polymer having functional group. The evaluation for adhesive property was carried out, and the results are shown in Table 1.

Examples 3 to 4 and Comparative Example 2

Coated plates were produced in the same manner as in Example 1 in case of Example 3, in Example 2 in case of Example 4 and in Comparative Example 1 in case of Comparative Example 2 except that a top layer was formed by using an aqueous coating composition comprising FEP (NEOFLON FEP Dispersion ND-1 available from DAIKIN INDUSTRIES, LTD) as a coating composition comprising a fluorine-containing polymer having no functional group. The evaluation for adhesive property was carried out, and the results are shown in Table 1.

Example 5

(1) Pre-treatment of Substrate

Pre-treatment was carried out in the same manner as in Example 1.

(2) Formation of Primer Layer Comprising Fluorine-containing Polymer having Functional Group

An aqueous dispersion comprising PFA having hydroxyl and prepared in Preparation Example 1 was applied to the plate by an air spray so that a coating thickness would become about 5 μm, followed by infrared-drying at 90° C. for 10 minutes.

(3) Formation of Layer (Top Layer) Comprising Fluorine-containing Polymer having no Functional Group

Onto the primer layer obtained in (2) above was applied a powder coating composition of PFA (NEOFLON PFA Powder Coating Composition ACX-31 available from DAIKIN INDUSTRIES, LTD.) as a coating composition of fluorine-containing polymer having no functional group by electrostatic coating so that a coating thickness would become 40 μm, followed by sintering at 380° C. for 20 minutes.

(4) Evaluation of Adhesive Property

The evaluation was carried out in the same manner as in Example 1, and the results are shown in Table 1.

Example 6

A coated plate was produced in the same manner as in Example 5 except that a primer layer was formed by using the aqueous dispersion comprising PFA having hydroxyl and obtained in Preparation Example 2 as a primer comprising a fluorine-containing polymer having functional group. The evaluation for adhesive property was carried out, and the results are shown in Table 1.

Comparative Example 3

A coated plate was produced in the same manner as in Example 5 except that a primer layer was formed by using the aqueous dispersion comprising PFA having no functional group and obtained in Preparation Example 3 instead of a primer comprising a fluorine-containing polymer having functional group. The evaluation for adhesive property was carried out, and the results are shown in Table 1.

Example 7

(Evaluation of Adhesive Property of PFA Powder Coating Composition having Hydroxyl)

(1) Production of Press Sheet for Adhesion Test

About 4 g of the PFA powder coating composition having hydroxyl and prepared in Preparation Example 7 was put in a cylindrical metal mold of 60 mm diameter and compression-molded at room temperature at a pressure of 300 kgf/cm² with a press machine to give a disc-like cold press sheet (hereinafter also referred to as “PFA sheet”).

(2) Pre-treatment of Substrate

A pure aluminum plate of 100×100×1 (mm) was degreased with acetone and then subjected to sand blasting.

(3) Production of Adhered Sample

The PFA sheet obtained in (1) above was placed on the aluminum plate ((2) above) and put in a hot air dryer to heat to melt at 330° C. for 10 minutes. Thus a sample produced by adhering the PFA sheet of about 450 μm thick to the aluminum plate was obtained. FIG. 1 shows a diagrammatic plan view of the adhered plate comprising the PFA sheet 1 and the aluminum plate 2.

(4) Measurement of Adhesive Strength

As shown in FIG. 1, the PFA sheet 1 of the adhered sample obtained in (3) above was cut with a cutter at intervals of a width a (10 mm) and one end of each strip-like sheet 1 was folded up, thus giving a test sample for measuring adhesive strength. FIG. 2 shows a diagrammatic perspective view of the test sample for measuring adhesive strength. As shown in FIG. 2, the sheet 1 was pulled up at an angle of 90° to the aluminum plate 2 to measure peeling strength. The adhesive strength was measured at room temperature at a cross head speed of 50 mm/min with TENSILON Universal Tester (available from Orientec Corporation). An adhesive strength was 5.5 kgf/cm as an average value of peel by area method.

Comparative Example 4

(Evaluation of Adhesive Property of PFA Powder Coating Composition having no Functional Group)

Production of a press sheet for adhesion test, pre-treatment of a substrate and production of an adhered sample were carried out in the same manner as in Example 7 except that the powder coating composition of PFA having no functional group and prepared in Preparation Example 8 was used instead of the powder coating composition of PFA having hydroxyl and prepared in Preparation Example 7. Then adhesive strength was measured.

Adhesive strength of the powder coating composition of PFA having no functional group was 0.8 kgf/cm.

Example 8

(Electrostatic Coating of PFA Powder Coating Composition having Hydroxyl)

Electrostatic coating of the PFA powder coating composition having hydroxyl and prepared in Preparation Example 7 was carried out on an aluminum plate pre-treated in the same manner as in Example 7 at room temperature at a voltage of 40 kV with an electrostatic coating machine (Model GX3300 available from Iwata Toso Kabushiki Kaisha). The coated plate was sintered at 330° C. for 15 minutes with a hot air dryer to give a coating film.

The coating film was a continuous uniform transparent film and was adhered strongly to the aluminum plate.

Comparative Example 5

(Heat Resistance of Fluorine-containing Polymer Prepared by Using Non-fluorine-containing Monomer having Functional Group)

Thermal decomposition temperature of the fluorine-containing polymer prepared in Preparation Example 9 was measured through TGA analysis, and 1% thermal decomposition temperature thereof was 220° C. From this, it was seen that heat resistance of the fluorine-containing polymer prepared by using a non-fluorine-containing monomer having functional group like the polymer obtained in Preparation Example 9 was low.

Further the fluorine-containing copolymer obtained in Preparation Example 9 was dissolved in butyl acetate in a concentration of 10% by weight.

Pre-treatment of a pure aluminum substrate, application of a primer layer comprising the fluorine-containing copolymer of Preparation Example 9 and application (electrostatic coating of PFA powder coating composition) of a top layer were carried out in the same manner as in Example 5 except that for the primer layer, the above-mentioned butyl acetate solution of the fluorine-containing copolymer of Preparation Example 9 was used instead of the aqueous dispersion of PFA having hydroxyl.

A coating film obtained by sintering at 380° C. for 20 minutes after the application was colored yellow-brown, and foaming and peeling were also seen. Thus a uniform transparent coating film could not be obtained.

Examples 9 to 12

(Adhesion Test of PFA Film having Hydroxyl to Metal)

Adhesion test of a PFA film having hydroxyl (film of Preparation Example 10 or 11) was carried out in the manner mentioned below by using, as a metal plate, degreased chromate-treated aluminum, pure aluminum and steel plates of 0.5 mm thick. The results are shown in Table 2.

(Production of Test Piece for Peeling Test)

FIG. 3 is a diagrammatic perspective view of a laminated article made to produce a test piece for peeling test. As shown in FIG. 3, the PFA film having hydroxyl and obtained in Preparation Example 10 or 11 as an adhesive layer 3 and a 0.1 mm thick spacer 4 (aluminum foil) were put between the two metal plates 5 and then set on a press machine of 350° C., followed by preheating (20 minutes) and then compressing at 50 kg/cm² for one minute to give a laminated article of length b (150 mm)×width c (70 mm).

Each thickness of the adhesive layer 3 of the obtained laminated articles was 0.1 mm. Further the laminated article was cut to a width d of 25 mm and the spacer portion was bent in the shape of T at a point apart by a distance e (100 mm) from one end of the laminated article to give a test piece for the peeling test. FIG. 4 is a diagrammatic perspective view of the obtained test piece for peeling test. In FIG. 4, numeral 3 represents the adhesive layer and numeral 5 represents the metal plates.

(Peeling Test)

The peeling test was carried out at room temperature at a cross head speed of 50 mm/min by using TENSILON Universal Tester available from Orientec Corporation according to T-type peeling test method of JIS K6854-1977. The results show the maximum peeling strength (kgf/25 mm) and minimum peeling strength (kgf/25 mm)

Comparative Examples 6 to 8

(Adhesion Test of PFA Film having no Functional Group to Metal)

Production of test pieces and peeling test were carried out in the same manner as in Example 9 except that the PFA film having no functional group and obtained in Preparation Example 12 was used instead of the PFA film having hydroxyl and obtained in Preparation Example 10 or 11. The results are shown in Table 2.

Examples 13 to 14

(Adhesion Test of PFA Film having Hydroxyl to Glass)

Adhesion test of PFA having hydroxyl to Pyrex glass plate of 30×20×5 mm was carried out in the manner mentioned below.

Further hot water resistance test and methanol dipping test of the laminated article after the adhesion were carried out. The results are shown in Table 3.

(Production of Test Piece for Tensile Shear Test)

FIG. 5 is a diagrammatic perspective view of a test piece for tensile shear test. As shown in Table 5, the PFA film having hydroxyl as an adhesive layer 3 which was obtained in Preparation Example 10 or 11 (length f of 10 m, width g of 20 mm, thickness h of 0.1 mm) was put between the Pyrex glass plates 6 (length i of 30 m, width g of 20 mm, thickness j of 5 mm), and a load of 3 kg was applied, followed by allowing to stand at 350° C. for 30 minutes in an electric oven to give a test piece. A thickness of the adhesive layer 3 was adjusted to 0.1 mm with a spacer.

(Adhesive Strength)

FIG. 6 is a diagrammatic perspective view of a test device to be used for measuring adhesive strength by tensile shearing method. As shown in FIG. 6, a test jig 8 matching the shape of the test piece 7 obtained as mentioned above was set on TENSILON Universal Tester 9 available from Orientec Corporation, and then the tensile shearing test was carried out at a cross head speed of 20 mm/min. The results of the measurement are shown by maximum adhesive strength (kgf/cm²).

(Hot Water Resistance Test)

The test piece obtained as mentioned above was dipped in 50° C. hot water to check to see adhesion after a lapse of 6 hours and measure adhesive strength (kgf/cm²) after a lapse of 72 hours.

(Methanol Dipping Test)

The test piece obtained as mentioned above was dipped in methanol of room temperature to check to see its adhesion.

Comparative Example 9

(Adhesion of PFA Film having no Functional Group to Glass)

Production of a test piece and various tests were carried out in the same manner as in Example 13 except that the PFA film having no functional group and obtained in Preparation Example 12 was used instead of the PFA film having hydroxyl and obtained in Preparation Example 10 or 11. The results are shown in Table 3.

Example 15

(Tests for Adhesion and Post-processability after Lamination of PFA Film having Hydroxyl to Stainless Steel)

A laminated test plate was produced in the manner mentioned below by using a degreased SUS304 stainless steel plate of 150 mm long×70 mm wide×0.5 mm thick as a metal plate. The PFA film having hydroxyl and produced in Preparation Example 13 and the PFA film having no functional group and produced in Preparation Example 14 were cut to the same size as the above-mentioned SUS plate.

Further a polyimide film (Kapton 200-H available from E. I. Du Pont de Nemours & Co.) which was used for separation was also cut to the same size as above.

FIG. 7 is a diagrammatic cross-sectional view of an obtained laminated test plate. As shown in FIG. 7, the PFA film 12 having hydroxyl, the PFA film 13 having no functional group and the polyimide film 14 were put between the two SUS plates 11, and then set on a press machine preset at 350° C., followed by preheating (20 minutes) and then pressing at 50 kgf/cm² for one minute to give a laminated test plate.

After cooling, when the SUS plate 11 contacting the polyimide film 14 was removed, the polyimide film was peeled from the interface with the PFA film 13 having no functional group spontaneously.

As a result, a three-layered laminated article having good transparency and comprising the PFA film 12 having hydroxyl as an adhesive layer, the SUS plate 11 and the PFA film 13 was obtained. FIG. 8 is a diagrammatic cross-sectional view of the obtained three-layered laminated article.

Further the obtained three-layered laminated article was cross-cut with a cutting knife so that a cut depth reached the surface of the SUS plate 11, and a hundred pieces of 1 mm squares of lattice pattern were made. A center of the squares was pushed out by 5 mm with Erichsen tester. As a result, the PFA film 12 having hydroxyl was not peeled off at all and kept adhered strongly to the SUS plate 11 which was a substrate.

The PFA film 12 exhibited strong adhesion to the SUS plate 11.

Comparative Example 10

(Tests for Adhesion and Post-processability after Lamination of PFA Film having no Functional Group to Stainless Steel)

A laminated article comprising the SUS plate 11 and the PFA film 13 having no functional group was produced in the same manner as in Example 15 except that the PFA film having hydroxyl was not used. FIG. 9 is a diagrammatic cross-sectional view of the obtained laminated article.

The PFA film 13 having no functional group seemed to be adhered, but could be peeled off from the SUS plate 11 easily.

Further Erichsen test was carried out in the same manner as in Example 15, and 60 pieces among 100 cross-cut squares were peeled off from the cut line.

Example 16

(Adhesion Test of PFA Film having Hydroxyl and Polyimide Film)

The PFA film 12 having hydroxyl and obtained in Preparation Example 13, the PFA film 13 having no functional group and obtained in Preparation Example 14 and the polyimide film 14 were cut to the same size as in Example 15, and put between the two SUS plates 11, followed by heating with a press machine in the same manner as in Example 15 to give a laminated test plate. FIG. 10 shows a diagrammatic cross-sectional view of the obtained laminated test plate. Then after cooling, the SUS plate 11 was removed to obtain a laminated article. FIG. 11 is a diagrammatic cross-sectional view of the obtained laminated article. Further the laminated article was cut to a width of 25 mm.

FIG. 12 is a diagrammatic cross-sectional view of the above-mentioned laminated article to be subjected to T-type peeling test. In FIG. 12, a part of interface between the polyimide film 14 and the PFA film 12 having hydroxyl was peeled, and the T-type peeling test by peeling in the direction of an arrow shown in FIG. 12 was carried out in the same manner as in Example 9. The adhesive strength was 4.0 kgf/25 mm as an average value of peel according to area method.

Comparative Example 11

(Adhesion Test of PFA Film having no Functional Group to Polyimide Film)

FIG. 13 is a diagrammatic cross-sectional view of a laminated article to be subjected to T-type peeling test in the same manner as in Example 1. In FIG. 13, a part of interface between the polyimide film 14 and the PFA film 13 having no functional group of the 25 mm wide laminated article obtained in Example 16 was peeled, and the T-type peeling test by peeling in the direction of an arrow shown in FIG. 13 was carried out in the same manner as in Example 16, but no adhesive property was exhibited.

Comparative Example 12

(Heat Resistance of Fluorine-containing Polymer Prepared by Using Non-fluorine-containing Monomer having Functional Group)

A thermal decomposition temperature of the fluorine-containing polymer obtained in Preparation Example 9 was measured through TGA analysis, and 1% thermal decomposition temperature was 220° C. From that, it was seen that the fluorine-containing polymer as prepared in Preparation Example 9 by using a non-fluorine-containing monomer having functional group has low heat resistance.

Further the fluorine-containing polymer prepared in Preparation Example 9 was dissolved in butyl acetate in a concentration of 10% by weight.

To the aluminum plate pre-treated in the same manner as in Example 9 was applied the above-mentioned butyl acetate solution of fluorine-containing polymer of Preparation Example 9 by an air spray so that a coating thickness would become about 10 μm, followed by infrared-drying at 90° C. for 10 minutes.

On the coating film 16 of the fluorine-containing polymer prepared by using a non-fluorine-containing monomer having functional group were placed in order the PFA film 13 having no functional group and prepared in Preparation Example 14, the polyimide film 14 for separation (same as in Example 15) and the aluminum plate 15, followed by heating and pressing at 350° C. with a press machine in the same manner as in Example 15 to give a laminated test plate. A diagrammatic cross-sectional view of the obtained laminated test plate is shown in FIG. 14.

After cooling the laminated test plate, the aluminum plate 15 contacting the polyimide film 14 and the polyimide film 14 were removed to give a laminated article.

The obtained laminated article was colored yellow-brown, and foaming and peeling occurred between the PFA film 13 and the aluminum plate 15. Thus a uniform transparent laminated article could not be obtained.

TABLE 2 Ex. 9 Ex. 10 Com. Ex. 6 Ex. 11 Com. Ex. 7 Ex. 12 Com. Ex. 8 Kind of fluorine- Prep. Ex. 10 Prep. Ex. 11 Prep. Ex. 12 Prep. Ex. 10 Prep. Ex. 12 Prep. Ex. 10 Prep. Ex. 12 containing adhesive Kind of metal plate Chromate- Chromate- Chromate- Pure Pure Dull- Dull- treated treated treated aluminum aluminum finished finished aluminum aluminum aluminum steel sheet steel sheet Maximum peeling 15.4 11.3 1.8  9.5 1.5  22.4 2.0  strength (kgf/25 mm) Minimum peeling  7.2  2.1 0.18 2.5 0.15 12.4 0.20 strength (kgf/25 mm)

TABLE 3 Ex. 13 Ex. 14 Com. Ex. 9 Kind of fluorine- Prep. Ex. 10 Prep. Ex. 11 Prep. Ex. 12 containing adhesive Kind of substrate Pyrex glass Pyrex glass Pyrex glass Adhesion strength 83 or more 83 or more 59 (kgf/cm²) Breaking of Breaking of Peeling glass glass Hot water test resistance (50° C.) 6 hours after Adhesion was Adhesion was Spontaneous maintained. maintained. peeling Adhesive strength 63 10 — (kgf/cm²) after 72-hour dipping Methanol dip test (room temperature) 24 hours after Adhesion was — Spontaneous maintained. peeling 72 hours after Adhesion was — — maintained.

Examples 17 to 18

Non-stickiness test was carried out through the method mentioned below by using a coated plate (Example 17) produced by electrostatically coating a PFA powder coating composition having hydroxyl and obtained in Example 8 and an extruded film (Example 18) of PFA having hydroxyl and obtained in Preparation Example 13. The results are shown in Table 4.

(Non-stickiness Test)

Measurement was made at 23° C.±2° C. FIG. 15 is a diagrammatic perspective view of a test piece used in the non-stickiness test. A test plate 17 was 150 mm or more in length, and stain thereon was wiped off with acetone. First a 18 mm wide adhesive tape 18 (JIS Z 1522) was cut to a length of 300 mm, and only 150 mm long portion k was placed on the test plate 17. The surface of the tape 18 was rubbed with a rubber eraser of JIS S 6050 to adhere the tape to the test plate to give an adhered portion 19. A paper was attached to the remaining 150 mm portion (not described) to make handling easy. After the adhering, the adhered test plate was allowed to stand for 20 minutes to adhere the tape 18 to the test plate 17 sufficiently. The tape 18 was peeled up to a width m of 25 mm from the end of the test plate 17 and the test plate 17 was mounted on a clamping device at the bottom of the tensile tester. The end of the peeled tape 18 was folded by 180° and fitted to an upper clamping device so that the tape 18 can be peeled straight. A peeling force of the tape 18 from the test plate 17 was measured with the tester at a stretching speed of 20 mm/min. The measured value is an average of measurement when the tape 18 is peeled smoothly. The results are shown in Table 4.

Comparative Examples 13 to 14

(Non-stickiness Test of PFA Film having no Functional Group)

A non-stickiness test was carried out in the same manner as in Example 17 by using an extruded PFA film having no functional group and obtained in Preparation Example 14 (Comparative Example 13) and a non-coated glass plate (Comparative Example 14). The results are shown in Table 4.

TABLE 4 Ex. 17 Ex. 18 Com. Ex. 13 Com. Ex. 14 Test sample Ex. 8 Prep. Ex. 13 Prep. Ex. 14 — Plate coated PFA film PFA film Glass plate with PFA having having no powder hydroxyl functional coating group composition having hydroxyl Non- 240 235 230 300 stickiness (gf/18 mm)

From Table 4, it was seen that PFA having OH group also has nearly the same excellent non-sticking property as PFA having no functional group.

Examples 19 to 20

Carbon contamination test and weather resistance test (only Example 20) were carried out through the method mentioned below by using, as a test plate (or film), the plate electrostatically coated with a PFA powder coating composition having hydroxyl which was obtained in Example 8 (Example 19) and the extruded PFA film having hydroxyl and obtained in Preparation Example 13 (Example 20).

{circle around (1)} Carbon Contamination Test

(Preparation of Carbon Solution)

Ten grams of a carbon powder (MA100 available from Mitsubishi Chemical Co., Ltd.) was added to 90 g of ion-exchanged water, and dispersed and mixed by using glass beads to give a dispersion of carbon.

(Coating of Carbon)

The dispersion of carbon was sprayed to the above-mentioned coated plate or the film at about 50 g/m² and heated at 80° C. for two hours to give a black test plate.

(Evaluation)

The obtained black test plate was exposed to flowing water while being brushed. Then a degree of contamination was observed with naked eyes and evaluated by the following criteria. The results are shown in Table 5.

◯: Contamination could be eliminated by washing, and the coated plate or film returned to nearly the state before the contamination test.

Δ: A part of contamination could be removed by washing, but a gray stain was attached to a whole surface of the coated plate or film as if it was soaking into the plate or film. The stain could not be removed.

x: A black stain remained over the surface of the coated plate or film, and could not be removed by washing with water.

{circle around (2)} Weather Resistance Test

The above-mentioned coated plate or film was put in I-SUPER UV tester (available from Iwasaki Denki Kabushiki Kaisha) and an accelerated weather resistance test was carried out to measure a water contact angle to the coated plate after having allowed to stand for 500 hours. The results are shown in Table 5.

Comparative Example 15

After the same aluminum plate as in Example 7 was subjected to 80 to 120 mesh sand blasting, a primer (POLYFLON TFE Enamel EK-1959 DGN available from DAIKIN INDUSTRIES, LTD) was sprayed to the plate and the coated plate was dried at 90° C. in an infrared drying oven to form a primer layer.

After a PFA powder coating composition (NEOFLON Powder Coating Composition ACX-31 available from DAIKIN INDUSTRIES, LTD.) was electrostatically coated on the primer layer, the coated plate was subjected to sintering at 350° C. for 30 minutes to give a plate having a coating film of PFA powder coating composition and a primer of grayish brown color.

Also with respect to the plate coated with a PFA powder coating composition, a carbon contamination test was carried out in the same manner as in Example 19. The results are shown in Table 5.

Comparative Example 16

A clear coating composition adjusted to OH/NCO ratio=1:1 was prepared by mixing 100 g of ZEFFLE GK510 (available from DAIKIN INDUSTRIES, LTD., OH value: 60) which is a varnish for cold curing type fluorine-containing resin coating composition, 10.5 g of isocyanate curing agent CORONATE HX (available from Nippon Polyurethane Co., Ltd.) and 120 g of butyl acetate.

The above-mentioned clear coating composition was spray-coated to an aluminum plate sand-blasted in the same manner as in Comparative Example 7, followed by sintering at 120° C. for 30 minutes to give a coated plate on which a coating film was formed. Also the same tests as in Example 20 were carried out by using the coated plate. The results are shown in Table 5.

Comparative Example 17

A coating composition adjusted to OH/NCO ratio=1:1 was prepared by mixing 100 g of ACRYDICK A801 (available from Dai-Nippon Ink Co., Ltd., OH value: 100) which is a varnish for cold curing type acrylic resin coating composition, 17 g of isocyanate curing agent CORONATE HX (same as in Comparative Example 4) and 120 g of butyl acetate. Spray-coating to an aluminum plate and sintering were carried out in the same manner as in Comparative Example 16 by using the obtained composition to give a coated plate on which a coating film was formed.

Also the same tests as in Example 20 were carried out by using the coated plate. The results are shown in Table 5.

TABLE 5 Ex. 19 Ex. 20 Com. Ex. 15 Com. Ex. 16 Com. Ex. 17 Test sample Plate coated with PFA film having Plate having a Plate coated with Plate coated with PFA powder hydroxyl of PFA powder a cold curing a cold curing coating Preparation coating type fluorine- type acrylic resin composition Example 13 composition layer containing resin coating having hydroxyl of adhered by using coating composition Example 8 a commercially composition available primer Appearance Transparent Transparent Grayish brown Transparent Transparent Evaluation in ∘ ∘ ∘ Δ Δ-x carbon contamination test Water contact 113 115 102 92 80 angle (degree) Water contact — 113 — 85 20 or lower angle in weather resistance test (degree)

Preparation Example 16

(Blend of PFA having no Functional Group and Carbon Fiber)

PFA having no functional group and prepared in Preparation Example 6 was blended uniformly with carbon fiber (KRECA CHOP M-207S available from Kureha Chemical Industry Co., Ltd.) at 80:20 (weight ratio) by using a rocking mixer, followed by kneading and extruding at 350° to 370° C. with a two screw extruder (LABOPLASTOMILL available from Toyo Seiki Kabushiki Kaisha) to give pellets.

Preparation Example 17

(Blend of PFA having no Functional Group with Aluminum Borate Whisker)

PFA having no functional group and prepared in Preparation Example 6 was blended uniformly with aluminum borate whisker (ALBOREX Y available from Shikoku Kasei Kogyo Kabushiki Kaisha) at 92:8 (weight ratio) by using a rocking mixer, followed by kneading and extruding at 350° to 370° C. with a two screw extruder (LABOPLASTOMILL available from Toyo Seiki Kabushiki Kaisha) to give pellets.

Preparation Example 18

(Production of Film of PFA Containing Carbon Fiber)

Compression molding was carried out in the same manner as in Preparation Example 10 except that PFA pellets containing carbon fiber and obtained in Preparation Example 16 were used instead of a white solid obtained in Preparation Example 4 to give a 0.5 mm thick PFA film containing carbon fiber.

Preparation Example 19

(Production of PFA Film Containing Aluminum Borate Whisker)

Compression molding was carried out in the same manner as in Preparation Example 10 except that PFA pellets containing aluminum borate whisker and obtained in Preparation Example 17 was used instead of a white solid obtained in Preparation Example 4 to give a 0.5 mm thick PFA film containing aluminum borate whisker.

Example 21

(Lamination of PFA Film Containing Carbon Fiber to Aluminum Plate)

A laminated test plate was produced in the manner mentioned below by using a degreased pure aluminum plate of 150 mm long×70 mm wide×0.5 mm thick as a metal plate. FIG. 16 is a diagrammatic cross-sectional view of an obtained laminated test plate.

As shown in FIG. 16, the PFA film 12 having hydroxyl and obtained in Preparation Example 13, the PFA film 20 containing carbon fiber and obtained in Preparation Example 18, the polyimide film 14 were put between the two aluminum plates 15, and a spacer 4 (0.1 mm thick aluminum foil) was inserted partly in the same layer as the PFA film 12 and then set on a press machine preset at 350° C., followed by preheating (20 minutes) and then pressing at 50 kgf/cm² for one minute. After cooling, the aluminum plate 15 contacting the polyimide film 14, the polyimide film 14 and the spacer 12 were removed to give a laminated article. FIG. 17 is a diagrammatic cross-sectional view of an obtained laminated article.

FIG. 18 is a diagrammatic cross-sectional view of the above-mentioned laminated article to be subjected to T-type peeling test. The PFA film 20 containing a filler (carbon fiber) and the aluminum plate 15 were pulled in the directions shown by arrows in FIG. 18 to carry out the T-type peeling test in the same manner as in Example 9. The adhesive strength was 4.8 kgf/25 mm as an average value of peel according to area method.

Example 22

(Lamination of PFA Film Containing Aluminum Borate Whisker to Aluminum Plate)

A laminated article of PFA containing aluminum borate whisker and aluminum plate was obtained in the same manner as in Example 21 except that the PFA film containing aluminum borate whisker and obtained in Preparation Example 19 was used instead of the PFA film containing carbon fiber and obtained in Preparation Example 18. Measurement of adhesive strength between the PFA layer containing aluminum borate whisker and the aluminum plate was carried out in the same manner as in Example 21 by T-type peeling test. The adhesive strength was 4.6 kgf/25 mm as an average value of peel according to area method.

Example 23

(Sliding Test)

The sliding test was carried out by using the composite material obtained by laminating the PFA film containing carbon fiber and obtained in Example 21 to the aluminum plate.

(Friction and Abrasion Test by Thrust)

{circle around (1)} Preparation of Test Sample and Counterpart Material

Aluminum die cast (ADC 12) was used as a counterpart material. A surface of PFA film containing carbon fiber of a composite material which was obtained by laminating the carbon fiber-containing PFA film produced in Example 21 on the aluminum plate and a contacting surface of the counterpart material were subjected to grinding with a grinder to give surface roughness of not more than RA 0.5 μm and Rmax of not more than 5 mm.

{circle around (2)} Friction and Abrasion Test

A coefficient of friction was measured at room temperature in the air at a speed of 60 m/min at a load of 5.0 kgf/cm² by using Suzuki-Matsubara type friction and abrasion tester available from Orientec Coropration. The results are shown in Table 6.

Example 24

A sliding test was carried out in the same manner as in Example 23 except that the composite material produced in Example 22 by laminating the PFA film containing aluminum borate whisker to an aluminum plate was used instead of the composite material produced in Example 21 by laminating a PFA film containing carbon fiber to an aluminum plate. The obtained coefficient of friction is shown in Table 6.

TABLE 6 Ex. 23 Ex. 24 Coefficient of friction 0.15 0.17

Example 25

(Heat Resistance of Adhesion of Plate Coated with PFA Powder Coating Composition having Hydroxyl)

(1) Production of Plate Coated with a Powder Coating Composition

An aluminum plate pre-treated in the same manner as in Example 7 was coated with a powder coating composition of PFA having hydroxyl and prepared in Preparation Example 7 at room temperature at a voltage of 40 kV by electrostatic coating by using an electrostatic powder coating machine (the same machine as in Example 8). The coated aluminum plate was sintered at 330° C. for 15 minutes to give a coating film. Onto the obtained coating film was applied a powder coating composition of PFA having no functional group (NEOFLON PFA Powder Coating Composition ACX-31 available from DAIKIN INDUSTRIES, LTD) by electrostatic coating in the same manner as above, followed by sintering at 380° C. for 20 minutes to give a transparent coating film having a total thickness of 159 μm.

(2) Measurement of Adhesive Strength

FIG. 19 is a diagrammatic perspective view of an aluminum plate 22 having a coating film obtained in (1) of Example 25. As shown in FIG. 19, the coating film 21 obtained in (1) above was cut with a cutter at intervals of a width n (10 mm) until the cutter reached the surface of the substrate, and one end of each cut strip of the coating film 21 was peeled. Thus a coated sample was obtained for measuring adhesive strength. FIG. 20 is a diagrammatic perspective view of the coated sample for measuring adhesive strength.

As shown in FIG. 20, the coating film 21 was pulled up at an angle of 90 degrees to the aluminum plate 22 and peeling strength was measured. The measurement was carried out at room temperature at a cross head speed of 50 mm/min by using TENSILON Universal Tester (the same one as in Example 7), and an average value of peel according to area method was assumed to be adhesive strength. The results are shown in Table 7.

(3) Measurement of Heat Resistance of Adhesion

A plate coated with a powder coating composition was produced separately in the same manner as in above (1), and put in a hot air dryer set at 300° C. After the lapse of 200 hours and 500 hours, the coated plate was taken out of the dryer. After the respective lapse of time, the coated plate was cooled to room temperature, and test sample was made and adhesive strength was measured in the same manner as in the above (2). The results are shown in Table 7.

Comparative Example 18

(Heat Resistance of Adhesion of Plate Coated with Powder Coating Composition and having Adhesive Primer Layer)

(1) Coating of Primer

An aluminum plate pre-treated in the same manner as in Example 7 was coated with a heat resisting primer for a fluorine-containing resin coating composition (POLYFLON TFE Enamel EK1959DGN available from DAIKIN INDUSTRIES, LTD.) by spraying so that the coating thickness would become about 10 μm, followed by sintering at 100° C. for 10 minutes.

(2) Production of Plate Coated with Powder Coating Composition

On the primer-coated plate of above (1) was applied only a PFA powder coating composition having no functional group (the same one as in Example 25) by electrostatic coating in the same manner as in (1) of Example 25, followed by sintering at 380° C. for 20 minutes to give a coating thickness of 126 μm including the primer layer.

(3) Measurement of Adhesive Strength

The same procedures as in (2) of Example 25 were repeated. The results are shown in Table 7.

(4) Measurement of Heat Resistance of Adhesion

The same procedures as in (3) of Example 25 were repeated. The results are shown in Table 7.

Examples 26 to 27

(Heat Resistance of Adhesion of Plate Coated with PFA Powder Coating Composition having Hydroxyl)

Plates coated with a powder coating composition were made and adhesive strength and heat resistance of adhesion were measured in the same manner as in Example 25 except that instead of the aluminum plate, a SUS430 stainless steel plate pre-treated in the same manner as in the aluminum plate (Example 26) and a galvanized steel plate subjected to only degreasing (Example 27) were used. The results are shown in Table 7.

Comparative Examples 19 to 20

Coated plates were made and adhesive strength and heat resistance of adhesion were measured in the same manner as in Comparative Example 18 except that instead of the aluminum plate, a SUS430 stainless steel plate pre-treated in the same manner as in the aluminum plate (Comparative Example 19) and a galvanized steel plate subjected to only degreasing (Comparative Example 20) were used. The results are shown in Table 7.

TABLE 7 Ex. 25 Ex. 26 Ex. 27 Com. Ex. 18 Com. Ex. 19 Com. Ex. 20 Laminated article Appearance Transparent Transparent Transparent Brown Brown Brown coating film coating film coating film Substrate Aluminum SUS430 Galvanized steel Aluminum SUS430 Galvanized steel plate plate Surface layer Film of PFA Film of PFA Film of PFA Film of PFA Film of PFA Film of PFA powder coating powder coating powder coating powder coating powder coating powder coating composition composition composition composition composition composition having no OH having no OH having no OH having no OH having no OH having no OH group 1) group 1) group 1) group 1) group 1) group 1) Adhesive layer Film of PFA Film of PFA Film of PFA Primer for Primer for Primer for powder coating powder coating powder coating fluorine-containing fluorine-containing fluorine-containing composition composition composition resin coating 3) resin coating 3) resin coating 3) having OH having OH having OH group 2) group 2) group 2) Coating 140-180 110-140 150-170 120-140 100-120 170-200 thickness (μm) Initial adhesive 1.7 1.6 not less than 2.0 2.0 2.0 0.9 strength (breakage of (kgf/cm) coating film) Heat resistance of adhesion Adhesive not less than 1.6 1.2 not less than 1.5 0.95 0.1 0.7 strength at (breakage of (breakage of 300° C. after coating film) coating film) 200 hours (kgf/cm) Adhesive not less than 1.6 1.1 1.0 0.2 not more than 0.1 0.4 strength at (breakage of 300° C. after coating film) 500 hours (kgf/ cm) 1) NEOFLON Powder Coating Composition ACX-31 available from DAIKIN INDUSTRIES, LTD. 2) Powder coating composition obtained in Preparation Example 7 3) POLYFLON TFE Enamel EK1959DGN available from DAIKIN INDUSTRIES, LTD.

Example 28

(Heat Resistance of Adhesion of Laminated Plate of PFA having Hydroxyl)

(1) Production of Laminated Plate

An aluminum plate pre-treated in the same manner as in Example 7 was used as a substrate. A PFA film having hydroxyl and obtained in Preparation Example 13 (thickness 100 μm), a PFA film having no functional group (NEOFLON PFA Film AF-0100 available from DAIKIN INDUSTRIES, LTD.) (thickness 100 μm) and a polyimide film for separation (the same one as in Example 15) were cut to the same size as the substrate.

FIG. 21 is a diagrammatic cross-sectional view of a laminated test plate. As shown in FIG. 21, the above-mentioned hydroxyl-containing PFA film 24, PFA film 25 having no functional group and polyimide film 26 were inserted between the two aluminum plates 23 (one is a substrate), and set on a press machine preset at 350° C., followed by preheating (for 20 minutes) and then pressing at 50 kgf/cm² for one minute. After cooling, the polyimide film 26 and aluminum plate 23 contacting the polyimide film 26 were removed to give a three-layered laminated article comprising the hydroxyl-containing PFA film 24 as an adhesive layer, aluminum plate 23 and PFA film 25. FIG. 22 is a diagrammatic cross-sectional view of the obtained three-layered laminated article.

(2) Adhesive Strength

A test sample for measuring adhesive strength was produced in the same manner as in (2) of Example 25 by using the laminated plate (three-layered laminated article) obtained in above (1) instead of the plate coated with a powder coating composition and obtained in (1) of Example 25, cutting at intervals of a width of 10 mm and peeling one end of each strip-like film from an interface between the aluminum plate and the hydroxyl-containing PFA film layer. The adhesive strength was measured in the same manner as in (2) of Example 25 by pulling up the peeled film at an angle of 90 degrees to the substrate. The results are shown in Table 8.

(3) Measurement of Heat Resistance of Adhesion

Another laminated plate of above (1) was produced separately, and measurement was made by using the produced laminated plate in the same manner as in (3) of Example 25. The results are shown in Table 8.

Examples 29 to 30

(Heat Resistance of Adhesion of Laminated Plate having Hydroxyl-containing PFA)

Production of laminated plates and measurements of adhesive strength and heat resistance of adhesion were carried out in the same manner as in Example 28 except that instead of the aluminum plate, a SUS430 stainless steel plate pre-treated in the same manner as in the aluminum plate (Example 29) and a galvanized steel plate subjected to only degreasing (Example 30) were used. The results are shown in Table 8.

Comparative Example 21

(Heat Resistance of Adhesion of Laminated Plate Produced by using Surface-treated Fluorine-containing Resin Film)

(1) Surface-treating of Fluorine-containing Resin Film

One surface of a PFA film having no functional group (NEOFLON PFA Film AF-0100 available from DAIKIN INDUSTRIES, LTD.) (thickness 100 μm) was surface-treated with TETRAETCH A (available from Kabushiki Kaisha Jyunkosha) by the method mentioned below. One surface of the PFA film (adhering surface) was wiped with acetone, and after drying, the wiped surface was coated with a solution of TETRAETCH A. After the TETRAETCH A solution was allowed to stand on the film for about 20 seconds, the film was washed with methanol and pure water and then dried. The treated surface turned brown. Further according to testing method of wettability of film described in JIS K-6768, wettability of the treated surface was determined by using a standard test solution of 40 dyn/cm. It was recognized that the surface was uniformly wet and had been treated sufficiently. Water contact angle of the treated surface was 61 degrees (110 degrees before treatment).

(2) Production of Laminated Plate

Two-liquid mixing type heat resisting epoxy adhesive (HITEMP HT-100L available from Kabushiki Kaisha Konishi) was coated on an aluminum plate pre-treated in the same manner as in Example 7. The surface-treated PFA film of above (1) was cut to the same size as the substrate, and its treated surface was brought into close contact to the adhesive layer of the substrate. After heating at 120° C. for one hour, sintering was carried out at 180° C. for 20 hours for curing and adhering the film to the substrate.

(3) Measurement of Adhesive Strength

A test sample for measuring adhesive strength was produced in the same manner as in (2) of Example 28 by using the laminated plate obtained in above (2) instead of the laminated plate obtained in Example 28, cutting at intervals of a width of 10 mm and peeling one end of each strip-like film from an interface between the PFA film and the adhesive layer. The adhesive strength was measured in the same manner as in (2) of Example 25 by pulling up the peeled film at an angle of 90 degrees to the substrate. The results are shown in Table 8.

(4) Measurement of Heat Resistance of Adhesion

Another laminated plate of above (2) was produced, and by using it, measurement was made in the same manner as in (3) of Example 25. The results are shown in Table 8.

Comparative Examples 22 to 23

(Heat Resistance of Adhesion of Laminated Plate Produced by Using Surface-treated Fluorine-containing Resin Film)

Surface-treating of a fluorine-containing resin film, production of laminated plates and measurements of adhesive strength and heat resistance of adhesion were carried out in the same manner as in Comparative Example 21 except that instead of the aluminum plate, a SUS430 stainless steel plate pre-treated in the same manner as in the aluminum plate (Comparative Example 22) and a galvanized steel plate subjected to only degreasing (Comparative Example 23) were used. The results are shown in Table 8.

Comparative Example 24

(Heat Resistance of Adhesion of Laminated Plate Produced by Using Surface-treated Film)

(1) Surface Treatment of Fluorine-containing Resin Film

A surface-treated FEP film (NEOFLON FEP Film NF-0100B1 available from DAIKIN INDUSTRIES, LTD., one side was surface-treated) (thickness 100 μm) was used instead of the PFA film of (1) of Comparative Example 21 surface-treated with TETRAETCH.

(2) Production of Laminated Plate

An epoxy adhesive was coated on a pre-treated aluminum plate and a surface-treated film was laminated on the coated aluminum plate in the same manner as in (2) of Comparative Example 21 except that the surface-treated FEP film of above (1) was used instead of the PFA film surface-treated with TETRAETCH.

(3) Measurement of Adhesive Strength

Production of a test sample and measurement of adhesive strength were carried out in the same manner as in Comparative Example 21 except that the laminated plate obtained in above (2) was used instead of the laminated plate which was produced by using PFA film treated with TETRAETCH in (2) of Comparative Example 21.

(4) Measurement of Heat Resistance of Adhesion

Another laminated plate of above (2) was produced, and by using it, measurement was carried out in the same manner as in (3) of Example 25. The results are shown in Table 8.

Comparative Examples 25 to 26

(Heat Resistance of Adhesion of Laminated Plate Produced by Using Surface-treated Fluorine-containing Resin Film)

Production of laminated plates and measurements of adhesive strength and heat resistance of adhesion were carried out in the same manner as in Comparative Example 24 except that instead of the aluminum plate, a SUS430 stainless steel plate pre-treated in the same manner as in the aluminum plate (Comparative Example 25) and a galvanized steel plate subjected to only degreasing (Comparative Example 26) were used. The results are shown in Table 8.

TABLE 8 Ex. 28 Ex. 29 Ex. 30 Com. Ex. 21 Com. Ex. 22 Com. Ex. 23 Laminated article Appearance Transparent Transparent Transparent Brown Brown Brown coating film coating film coating film Substrate Aluminum SUS430 Galvanized steel Aluminum SUS430 Galvanized steel plate plate Surface layer Powder coating Powder coating Powder coating PFA film PFA film PFA film film of PFA film of PFA film of PFA surface-treated surface-treated surface-treated having no OH having no OH having no OH with TETRAETCH with TETRAETCH with TETRAETCH group 1) group 1) group 1) Adhesive layer PFA film having PFA film having PFA film having Heat resisting Heat resisting Heat resisting OH group 2) OH group 2) OH group 2) epoxy adhesive epoxy adhesive epoxy adhesive 3) 3) 3) Coating 180-220 170-200 200-230 150-190 160-190 170-190 thickness (μm) Initial adhesive 2.1 2.5 2.2 1.6 1.0 1.6 strength (kgf/cm) Heat resistance of adhesion Adhesive not less than 2.0 2.2 not less than 2.0 Spontaneous Spontaneous Spontaneous strength at (breakage of (breakage of peeling peeling peeling 300° C. after film) film) (peeling at (peeling at (peeling at 200 hours substrate side) substrate side) substrate side) (kgf/cm) Adhesive not less than 2.0 not less than 1.6 not less than 2.0 Spontaneous Spontaneous Spontaneous strength at (breakage of (breakage of (breakage of peeling peeling peeling 300° C. after film) film) film) (peeling at (peeling at (peeling at 500 hours substrate side) substrate side) substrate side) (kgf/cm) Com. Ex. 24 Com. Ex. 25 Com. Ex. 26 Laminated article Appearance Brown Brown Brown Substrate Aluminum SUS430 Galvanized steel plate Surface layer Surface-treated Surface-treated Surface-treated FEP film FEP film FEP film 4) 4) 4) Adhesive layer Heat resistive Heat resistive Heat resistive epoxy adhesive epoxy adhesive epoxy adhesive 3) 3) 3) Coating 130-160 160-180 160-180 thickness (μm) Initial adhesive 1.5 1.5 1.5 strength (kgf/cm) Heat resistance of adhesion Adhesive Spontaneous Spontaneous Spontaneous strength at peeling (peeling at peeling (peeling at peeling (peeling at 300° C. after substrate substrate substrate 200 hours side) side) side) (kgf/cm) Adhesive Spontaneous Spontaneous Spontaneous strength at peeling (peeling at peeling (peeling at peeling (peeling at 300° C. after substrate substrate substrate 500 hours side) side) side) (kgf/cm) 1) NEOFLON PFA Film AF-0100 available from DAIKIN INDUSTRIES, LTD. 2) Film obtained in Preparation Example 13 3) HITEMP HT-100L available from Kabushiki Kaisha Konishi 4) NEOFLON FEP Film NF-0100B1 available from DAIKIN INDUSTRIES, LTD.

Example 31

(Adhesion of Laminated Plate of PTFE Containing a Filler)

(1) Production of Laminated Plate

An aluminum plate of 150×70×5 mm subjected to only degreasing was used as a substrate. A three layered laminated article comprising a film (one obtained in Preparation Example 13) of PFA having functional group as an adhesive layer, PTFE containing a filler and aluminum plate was produced in the same manner as in Example 28 except that the above-mentioned aluminum plate was used and a sheet of 0.5 mm thick obtained by molding PTFE (POLYFLON TFE Molding Powder MG-2030 available from DAIKIN INDUSTRIES, LTD.) containing 15% by weight of graphite was used instead of a PFA film having no functional group.

(2) Adhesive Strength

An adhesive strength was measured by peeling the PTFE layer containing a filler and pulling the sheet of 10 mm wide at an angle of 90 degrees to the substrate in the same manner as in (2) of Example 28. The results are shown in Table 9.

Examples 32 to 34

(Adhesion of Laminated Plate of PTFE Containing a Filler)

Production of a laminated plate of aluminum and measurement of adhesive strength were carried out in the same manner as in Example 31 except that instead of the PTFE film containing graphite, a sheet of 0.5 mm thick obtained by molding PTFE (POLYFLON TFE Molding Powder MG1431 available from DAIKIN INDUSTRIES, LTD.) containing 15% of glass fiber and 5% of molybdenum disulfide was used (Example 32), a sheet of 0.5 mm thick obtained by molding PTFE containing 60% of bronze and 10% of carbon fiber was used (Example 33) and a sheet of 0.5 mm thick obtained by molding PTFE containing 20% of aromatic polyester resin (ECONOL available from Sumitomo Chemical Industries Co., Ltd.) was used (Example 34). The results are shown in Table 9.

Example 35

(Adhesion of Laminated Plate of PTFE Containing a Filler)

A laminated article comprising an adhesive layer of PFA having functional group, PTFE containing graphite and SUS plate was produced in the same manner as in Example 31 except that a SUS plate of 150×70×2.5 mm subjected to degreasing was used as a substrate instead of an aluminum plate, and an adhesive strength was measured. The results are shown in Table 9.

Examples 36 to 38

(Adhesion of Laminated Plate of PTFE Containing a Filler)

Production of a laminated plate of SUS304 and measurement of adhesive strength were carried out in the same manner as in Example 35 except that instead of the PTFE film containing graphite, a sheet of 0.5 mm thick obtained by molding PTFE (POLYFLON TFE Molding Powder MG1431 available from DAIKIN INDUSTRIES, LTD.) containing 15% of glass fiber and 5% of molybdenum disulfide was used (Example 36), a sheet of 0.5 mm thick obtained by molding PTFE containing 60% of bronze and 10% of carbon fiber was used (Example 37) and a sheet of 0.5 mm thick obtained by molding PTFE containing 20% of aromatic polyester resin (ECONOL available from Sumitomo Chemical Industries Co., Ltd.) was used (Example 38). The results are shown in Table 9.

Comparative Example 27

The same procedures as in Example 31 were repeated except that the PFA film having functional group used as an adhesive layer was not used, to give a laminated article comprising a PTFE sheet containing 15% of graphite (the same one as in Example 31) and an aluminum plate. An adhesive strength was measured and the results are shown in Table 9.

Comparative Examples 28 to 30

Production of a laminated plate comprising an aluminum plate and PTFE containing a filler and measurement of adhesive strength were carried out in the same manner as in Comparative Example 27 except that instead of the PTFE sheet containing 15% of graphite, the PTFE sheet of Example 32 containing 15% of glass fiber and 5% of molybdenum disulfide was used (Comparative Example 28), the PTFE sheet of Example 33 containing 60% of bronze and 10% of carbon fiber was used (Comparative Example 29) and the PTFE sheet of Example 34 containing 20% of aromatic polyester resin was used (Comparative Example 30). The results are shown in Table 9.

Comparative Example 31

The same procedures as in Example 35 were repeated except that the PFA film having functional group used as an adhesive layer was not used, to give a laminated article comprising a PTFE sheet containing 15% of graphite (the same one as in Example 35) and a SUS plate. An adhesive strength was measured and the results are shown in Table 9.

Comparative Examples 32 to 34

Production of a laminated plate comprising a SUS plate and PTFE containing a filler and measurement of adhesive strength were carried out in the same manner as in Comparative Example 31 except that instead of the PTFE sheet containing 15% of graphite, the PTFE sheet of Example 36 containing 15% of glass fiber and 5% of molybdenum disulfide was used (Comparative Example 32), the PTFE sheet of Example 37 containing 60% of bronze and 10% of carbon fiber was used (Comparative Example 33) and the PTFE sheet of Example 38 containing 20% of aromatic polyester resin was used (Comparative Example 34). The results are shown in Table 9.

TABLE 9 Adhesion Substrate Surface layer Adhesive layer (kgf/cm) Ex. 31 Aluminum PTFE containing OH-containing 2.3 graphite PFA 1) Com. Aluminum PTFE containing — Not adhered Ex. 27 graphite Ex. 32 Aluminum PTFE containing OH-containing 2.8 glass fiber and PFA molybdenum disulfide Com. Aluminum PTFE containing — Not adhered Ex. 28 glass fiber and molybdenum disulfide Ex. 33 Aluminum PTFE containing OH-containing 3.0 bronze and carbon PFA fiber Com. Aluminum PTFE containing — Not adhered Ex. 29 bronze and carbon fiber Ex. 34 Aluminum PTFE containing OH-containing 3.6 aromatic polyester PFA Com. Aluminum PTFE containing — Not adhered Ex. 30 aromatic polyester Ex. 35 SUS304 PTFE containing OH-containing 2.0 graphite PFA Com. SUS304 PTFE containing — Not adhered Ex. 31 graphite Ex. 36 SUS304 PTFE containing OH-containing 2.6 glass fiber and PFA molybdenum disulfide Com. SUS304 PTFE containing — Not adhered Ex. 32 glass fiber and molybdenum disulfide Ex. 37 SUS304 PTFE containing OH-containing 2.7 bronze and carbon PFA fiber Com. SUS304 PTFE containing — Not adhered Ex. 33 bronze and carbon fiber Ex. 38 SUS304 PTFE containing OH-containing 3.3 aromatic polyester PFA Com. SUS304 PTFE containing — Not adhered Ex. 34 aromatic polyester

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to obtain a composite material having sliding property which is produced by applying, to a substrate, a material comprising a fluorine-containing polymer having excellent adhesive property, without necessitating complicated steps. Further according to the present invention, it is possible to obtain the composite material which is excellent in heat resistance, stain-proofing property, non-sticking property, water- and oil-repelling property, stain removing property, chemical resistance, rust-preventive property, antibacterial property, resistance to energy ray and friction resistance and can be used suitably in the fields of office automation-related equipment, cars, electric appliances and chemical industries. 

What is claimed is:
 1. A method of endowing a sliding laminated article with a heat resistance of adhesion which comprises applying, between a substrate and a surface layer, a material comprising a fluorine-containing ethylenic polymer having functional group prepared by copolymerizing: (a) 0.05 to 30% by mole of at least one of fluorine-containing ethylenic monomers having at least one functional group selected from the group consisting of hydroxyl, carboxyl, a carboxylic salt group and epoxy, and (b) 70 to 99.95% by mole of at least one of fluorine-containing ethylenic monomers which do not have said functional group, said surface layer comprising a layer of a fluorine-containing ethylenic polymer having no functional group.
 2. The method of claim 1 which comprises applying, between the substrate and the surface layer, the fluorine-containing ethylenic polymer having functional group, wherein the fluorine-containing ethylenic monomer (b) which does not have said functional group is tetrafluoroethylene.
 3. The method of claim 1 which comprises applying, between the substrate and the surface layer, the fluorine-containing ethylenic polymer having functional group, wherein the fluorine-containing ethylenic monomer (b) which does not have said functional group is a monomer mixture of 85 to 99.7% by mole of tetrafluoroethylene and 0.3 to 15% by mole of a monomer represented by the formula (2): CF₂═CF—R_(f) ¹  (2) wherein R_(f) ¹ is CF₃ or OR_(f) ², in which R_(f) ² is a perfluoroalkyl group having 1 to 5 carbon atoms.
 4. The method of claim 1, which comprises applying the fluorine-containing ethylenic polymer having functional group between the substrate and the surface layer in the form selected from the group consisting of a coating composition, an aqueous dispersion, a powder coating composition and a film.
 5. The method of claim 1, wherein the substrate is one selected from the group consisting of a metallic substrate, a glass substrate, a ceramic substrate and a synthetic resin substrate.
 6. The method of claim 1, wherein the surface layer contains a filler.
 7. The method of claim 1, wherein the fluorine-containing polymer having no functional group of the surface layer is polytetrafluoroethylene, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer, tetrafluoroethylene-hexafluoropropylene copolymer or ethylene-tetrafluoroethylene copolymer.
 8. A method of endowing a sliding laminated article with a heat resistance of adhesion which comprises applying, between a substrate and a surface layer, a material comprising a fluorine-containing ethylenic polymer having functional group prepared by copolymerizing; (a) 0.05 to 30% by mole of at least one of fluorine-containing ethylenic monomers having at least one functional group selected from the group consisting of hydroxyl, carboxyl, a carboxylic salt group, a carboxylic ester group and epoxy, and (b) 70 to 99.95% by mole of at least one of fluorine-containing ethylenic monomers which do not have said functional group, wherein said fluorine-containing ethylenic monomer (a) having functional group is represented by the formula (1): CX₂═CX¹—R_(f)—Y  (1) wherein Y is —CH₂OH, —COOH, a carboxylic salt group, a carboxylic ester group or epoxy, X and X¹ are the same or different and each is hydrogen atom or fluorine atom, R_(f) is a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms, a fluorine-containing oxyalkylene group having 1 to 40 carbon atoms, a fluorine-containing alkylene group having ether bond and 1 to 40 carbon atoms or a fluorine-containing oxyalkylene group having ether bond and 1 to 40 carbon atoms, said surface layer comprising a layer of a fluorine-containing ethylenic polymer having no functional group.
 9. The method of claim 8, which comprises applying, between the substrate and the surface layer, the fluorine-containing ethylenic polymer having functional group, wherein the fluorine-containing ethylenic monomer (b) which does not have said functional group is tetrafluoroethylene.
 10. The method of claim 8, which comprises applying, between the substrate and the surface layer, the fluorine-containing ethylenic polymer having functional group, wherein the fluorine-containing ethylenic monomer (b) which does not have said functional group is a monomer mixture of 85 to 99.7% by mole of tetrafluoroethylene and 0.3 to 15% by mole of a monomer represented by the formula (2): CF₂═CF—R_(f) ¹  (2) wherein R_(f) ¹ is CF₃ or OR_(f) ², in which R_(f) ² is a perfluoroalkyl group having 1 to 5 carbon atoms.
 11. The method of claim 8, which comprises applying the fluorine-containing ethylenic polymer having functional group between the substrate and the surface layer in the form selected from the group consisting of a coating composition, an aqueous dispersion, a powder coating composition and a film.
 12. The method of claim 8, wherein the substrate is one selected from the group consisting of a metallic substrate, a glass substrate, a ceramic substrate and a synthetic resin substrate.
 13. The method of claim 8, wherein the surface layer contains a filler.
 14. The method of claim 8, wherein the fluorine-containing polymer having no functional group of the surface layer is polytetrafluoroethylene, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer, tetrafluoroethylene-hexafluoropropylene copolymer or ethylene-tetrafluoroethylene copolymer. 